1 | # Highlight.js
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2 |
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3 | [](https://www.npmjs.com/package/highlight.js)
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4 | [](https://join.slack.com/t/highlightjs/shared_invite/zt-mj0utgqp-TNFf4VQICnDnPg4zMHChFw)
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5 | [](https://discord.gg/M24EbU7ja9)
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6 | [](https://github.com/highlightjs/highlight.js/blob/main/LICENSE)
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7 | [](https://packagephobia.now.sh/result?p=highlight.js)
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8 | 
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9 | [](https://www.npmjs.com/package/highlight.js)
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10 | [](https://www.jsdelivr.com/package/gh/highlightjs/cdn-release)
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11 | 
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12 | [](https://lgtm.com/projects/g/highlightjs/highlight.js/?mode=list)
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13 |
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14 | [](https://github.com/highlightjs/highlight.js/actions?query=workflow%3A%22Node.js+CI%22)
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15 | [](https://github.com/highlightjs/highlight.js/issues)
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16 | [](https://github.com/highlightjs/highlight.js/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+welcome%22)
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17 | [](https://github.com/highlightjs/highlight.js/issues?q=is%3Aopen+is%3Aissue+label%3A%22beginner+friendly%22)
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18 | [](https://snyk.io/test/github/highlightjs/highlight.js?targetFile=package.json)
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19 |
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20 | <!-- [](https://github.com/highlightjs/highlight.js/actions?query=workflow%3A%22Node.js+CI%22) -->
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21 | <!-- [](https://github.com/highlightjs/highlight.js/commits/main) -->
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22 | <!-- [](https://www.jsdelivr.com/package/gh/highlightjs/cdn-release) -->
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23 | <!-- []() -->
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24 | <!-- [](https://bundlephobia.com/result?p=highlight.js) -->
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25 |
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26 |
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27 | Highlight.js is a syntax highlighter written in JavaScript. It works in
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28 | the browser as well as on the server. It works with pretty much any
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29 | markup, doesn’t depend on any framework, and has automatic language
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30 | detection.
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31 |
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32 | #### Upgrading to Version 10
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33 |
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34 | Version 10 is one of the biggest releases in quite some time. If you're
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35 | upgrading from version 9, there are some breaking changes and things you may
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36 | want to double check first.
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37 |
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38 | Please read [VERSION_10_UPGRADE.md](https://github.com/highlightjs/highlight.js/blob/main/VERSION_10_UPGRADE.md) for high-level summary of breaking changes and any actions you may need to take. See [VERSION_10_BREAKING_CHANGES.md](https://github.com/highlightjs/highlight.js/blob/main/VERSION_10_BREAKING_CHANGES.md) for a more detailed list and [CHANGES.md](https://github.com/highlightjs/highlight.js/blob/main/CHANGES.md) to learn what else is new.
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39 |
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40 | ##### Support for older versions
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41 |
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42 | Please see [SECURITY.md](https://github.com/highlightjs/highlight.js/blob/main/SECURITY.md) for support information.
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43 |
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44 | ## Getting Started
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45 |
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46 | The bare minimum for using highlight.js on a web page is linking to the
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47 | library along with one of the styles and calling [`highlightAll`][1]:
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48 |
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49 | ```html
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50 | <link rel="stylesheet" href="/path/to/styles/default.css">
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51 | <script src="/path/to/highlight.min.js"></script>
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52 | <script>hljs.highlightAll();</script>
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53 | ```
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54 |
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55 | This will find and highlight code inside of `<pre><code>` tags; it tries
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56 | to detect the language automatically. If automatic detection doesn’t
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57 | work for you, you can specify the language in the `class` attribute:
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58 |
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59 | ```html
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60 | <pre><code class="html">...</code></pre>
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61 | ```
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62 |
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63 | Classes may also be prefixed with either `language-` or `lang-`.
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64 |
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65 | ```html
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66 | <pre><code class="language-html">...</code></pre>
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67 | ```
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68 |
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69 | ### Plaintext and Disabling Highlighting
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70 |
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71 | To style arbitrary text like code, but without any highlighting, use the
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72 | `plaintext` class:
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73 |
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74 | ```html
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75 | <pre><code class="plaintext">...</code></pre>
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76 | ```
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77 |
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78 | To disable highlighting of a tag completely, use the `nohighlight` class:
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79 |
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80 | ```html
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81 | <pre><code class="nohighlight">...</code></pre>
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82 | ```
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83 |
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84 | ### Supported Languages
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85 |
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86 | Highlight.js supports over 180 different languages in the core library. There are also 3rd party
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87 | language plugins available for additional languages. You can find the full list of supported languages
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88 | in [SUPPORTED_LANGUAGES.md][9].
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89 |
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90 | ## Custom Scenarios
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91 |
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92 | When you need a bit more control over the initialization of
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93 | highlight.js, you can use the [`highlightBlock`][3] and [`configure`][4]
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94 | functions. This allows you to better control *what* to highlight and *when*.
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95 |
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96 | Here’s the equivalent of calling [`highlightAll`][1] using
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97 | only vanilla JS:
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98 |
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99 | ```js
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100 | document.addEventListener('DOMContentLoaded', (event) => {
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101 | document.querySelectorAll('pre code').forEach((block) => {
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102 | hljs.highlightBlock(block);
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103 | });
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104 | });
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105 | ```
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106 |
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107 | Please refer to the documentation for [`configure`][4] options.
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108 |
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109 |
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110 | ### Using custom HTML elements for code blocks
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111 |
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112 | We strongly recommend `<pre><code>` wrapping for code blocks. It's quite
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113 | semantic and "just works" out of the box with zero fiddling. It is possible to
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114 | use other HTML elements (or combos), but you may need to pay special attention to
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115 | preserving linebreaks.
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116 |
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117 | Let's say your markup for code blocks uses divs:
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118 |
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119 | ```html
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120 | <div class='code'>...</div>
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121 | ```
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122 |
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123 | To highlight such blocks manually:
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124 |
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125 | ```js
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126 | // first, find all the div.code blocks
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127 | document.querySelectorAll('div.code').forEach(block => {
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128 | // then highlight each
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129 | hljs.highlightBlock(block);
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130 | });
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131 | ```
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132 |
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133 | Without using a tag that preserves linebreaks (like `pre`) you'll need some
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134 | additional CSS to help preserve them. You could also [pre and post-process line
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135 | breaks with a plug-in][brPlugin], but *we recommend using CSS*.
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136 |
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137 | [brPlugin]: https://github.com/highlightjs/highlight.js/issues/2559
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138 |
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139 | To preserve linebreaks inside a `div` using CSS:
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140 |
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141 | ```css
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142 | div.code {
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143 | white-space: pre;
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144 | }
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145 | ```
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146 |
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147 |
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148 | ## Using with Vue.js
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149 |
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150 | Simply register the plugin with Vue:
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151 |
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152 | ```js
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153 | Vue.use(hljs.vuePlugin);
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154 | ```
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155 |
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156 | And you'll be provided with a `highlightjs` component for use
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157 | in your templates:
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158 |
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159 | ```html
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160 | <div id="app">
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161 | <!-- bind to a data property named `code` -->
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162 | <highlightjs autodetect :code="code" />
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163 | <!-- or literal code works as well -->
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164 | <highlightjs language='javascript' code="var x = 5;" />
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165 | </div>
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166 | ```
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167 |
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168 | ## Web Workers
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169 |
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170 | You can run highlighting inside a web worker to avoid freezing the browser
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171 | window while dealing with very big chunks of code.
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172 |
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173 | In your main script:
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174 |
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175 | ```js
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176 | addEventListener('load', () => {
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177 | const code = document.querySelector('#code');
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178 | const worker = new Worker('worker.js');
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179 | worker.onmessage = (event) => { code.innerHTML = event.data; }
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180 | worker.postMessage(code.textContent);
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181 | });
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182 | ```
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183 |
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184 | In worker.js:
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185 |
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186 | ```js
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187 | onmessage = (event) => {
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188 | importScripts('<path>/highlight.min.js');
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189 | const result = self.hljs.highlightAuto(event.data);
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190 | postMessage(result.value);
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191 | };
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192 | ```
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193 |
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194 | ## Node.js
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195 |
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196 | You can use highlight.js with node to highlight content before sending it to the browser.
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197 | Make sure to use the `.value` property to get the formatted html.
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198 | For more info about the returned object refer to the [api docs](https://highlightjs.readthedocs.io/en/latest/api.html).
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199 |
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200 |
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201 | ```js
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202 | // require the highlight.js library, including all languages
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203 | const hljs = require('./highlight.js');
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204 | const highlightedCode = hljs.highlightAuto('<span>Hello World!</span>').value
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205 | ```
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206 |
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207 | Or for a smaller footprint... load just the languages you need.
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208 |
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209 | ```js
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210 | const hljs = require('highlight.js/lib/core'); // require only the core library
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211 | // separately require languages
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212 | hljs.registerLanguage('xml', require('highlight.js/lib/languages/xml'));
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213 |
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214 | const highlightedCode = hljs.highlight('<span>Hello World!</span>', {language: 'xml'}).value
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215 | ```
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216 |
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217 |
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218 | ## ES6 Modules
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219 |
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220 | First, you'll likely install via `npm` or `yarn` -- see [Getting the Library](#getting-the-library) below.
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221 |
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222 | In your application:
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223 |
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224 | ```js
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225 | import hljs from 'highlight.js';
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226 | ```
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227 |
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228 | The default import imports all languages. Therefore it is likely to be more efficient to import only the library and the languages you need:
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229 |
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230 | ```js
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231 | import hljs from 'highlight.js/lib/core';
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232 | import javascript from 'highlight.js/lib/languages/javascript';
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233 | hljs.registerLanguage('javascript', javascript);
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234 | ```
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235 |
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236 | To set the syntax highlighting style, if your build tool processes CSS from your JavaScript entry point, you can also import the stylesheet directly as modules:
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237 |
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238 | ```js
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239 | import hljs from 'highlight.js/lib/core';
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240 | import 'highlight.js/styles/github.css';
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241 | ```
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242 |
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243 |
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244 | ## Getting the Library
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245 |
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246 | You can get highlight.js as a hosted, or custom-build, browser script or
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247 | as a server module. Right out of the box the browser script supports
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248 | both AMD and CommonJS, so if you wish you can use RequireJS or
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249 | Browserify without having to build from source. The server module also
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250 | works perfectly fine with Browserify, but there is the option to use a
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251 | build specific to browsers rather than something meant for a server.
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252 |
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253 |
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254 | **Do not link to GitHub directly.** The library is not supposed to work straight
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255 | from the source, it requires building. If none of the pre-packaged options
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256 | work for you refer to the [building documentation][6].
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257 |
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258 | **On Almond.** You need to use the optimizer to give the module a name. For
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259 | example:
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260 |
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261 | ```bash
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262 | r.js -o name=hljs paths.hljs=/path/to/highlight out=highlight.js
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263 | ```
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264 |
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265 | ### CDN Hosted
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266 |
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267 | A prebuilt version of Highlight.js bundled with many common languages is hosted by several popular CDNs.
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268 | When using Highlight.js via CDN you can use Subresource Integrity for additional security. For details
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269 | see [DIGESTS.md](https://github.com/highlightjs/cdn-release/blob/main/DIGESTS.md).
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270 |
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271 | **cdnjs** ([link](https://cdnjs.com/libraries/highlight.js))
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272 |
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273 | ```html
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274 | <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.3/styles/default.min.css">
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275 | <script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.3/highlight.min.js"></script>
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276 | <!-- and it's easy to individually load additional languages -->
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277 | <script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.7.3/languages/go.min.js"></script>
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278 | ```
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279 |
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280 | **jsdelivr** ([link](https://www.jsdelivr.com/package/gh/highlightjs/cdn-release))
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281 |
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282 | ```html
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283 | <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@10.7.3/build/styles/default.min.css">
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284 | <script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@10.7.3/build/highlight.min.js"></script>
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285 | <!-- and it's easy to individually load additional languages -->
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286 | <script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@10.7.3/build/languages/go.min.js"></script>
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287 | ```
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288 |
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289 | **unpkg** ([link](https://unpkg.com/browse/@highlightjs/cdn-assets/))
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290 |
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291 | ```html
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292 | <link rel="stylesheet" href="https://unpkg.com/@highlightjs/cdn-assets@10.7.3/styles/default.min.css">
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293 | <script src="https://unpkg.com/@highlightjs/cdn-assets@10.7.3/highlight.min.js"></script>
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294 | <!-- and it's easy to individually load additional languages -->
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295 | <script src="https://unpkg.com/@highlightjs/cdn-assets@10.7.3/languages/go.min.js"></script>
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296 | ```
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297 |
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298 | **Note:** *The CDN-hosted `highlight.min.js` package doesn't bundle every language.* It would be
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299 | very large. You can find our list of "common" languages that we bundle by default on our [download page][5].
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300 |
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301 | ### Self Hosting
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302 |
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303 | The [download page][5] can quickly generate a custom bundle including only the languages you need.
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304 |
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305 | Alternatively, you can build a browser package from [source](#source):
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306 |
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307 | ```
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308 | node tools/build.js -t browser :common
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309 | ```
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310 |
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311 | See our [building documentation][6] for more information.
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312 |
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313 | **Note:** Building from source should always result in the smallest size builds. The website download page is optimized for speed, not size.
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314 |
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315 |
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316 | #### Prebuilt CDN assets
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317 |
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318 | You can also download and self-host the same assets we serve up via our own CDNs. We publish those builds to the [cdn-release](https://github.com/highlightjs/cdn-release) GitHub repository. You can easily pull individual files off the CDN endpoints with `curl`, etc; if say you only needed `highlight.min.js` and a single CSS file.
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319 |
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320 | There is also an npm package [@highlightjs/cdn-assets](https://www.npmjs.com/package/@highlightjs/cdn-assets) if pulling the assets in via `npm` or `yarn` would be easier for your build process.
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321 |
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322 |
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323 | ### NPM / Node.js server module
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324 |
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325 | Highlight.js can also be used on the server. The package with all supported languages can be installed from NPM or Yarn:
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326 |
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327 | ```bash
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328 | npm install highlight.js
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329 | # or
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330 | yarn add highlight.js
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331 | ```
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332 |
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333 | Alternatively, you can build it from [source](#source):
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334 |
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335 | ```bash
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336 | node tools/build.js -t node
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337 | ```
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338 |
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339 | See our [building documentation][6] for more information.
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340 |
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341 |
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342 | ### Source
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343 |
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344 | [Current source][10] is always available on GitHub.
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345 |
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346 |
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347 | ## License
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348 |
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349 | Highlight.js is released under the BSD License. See [LICENSE][7] file
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350 | for details.
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351 |
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352 |
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353 | ## Links
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354 |
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355 | The official site for the library is at <https://highlightjs.org/>.
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356 |
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357 | Further in-depth documentation for the API and other topics is at
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358 | <http://highlightjs.readthedocs.io/>.
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359 |
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360 | A list of the Core Team and contributors can be found in the [CONTRIBUTORS.md][8] file.
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361 |
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362 | [1]: http://highlightjs.readthedocs.io/en/latest/api.html#highlightall
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363 | [2]: http://highlightjs.readthedocs.io/en/latest/css-classes-reference.html
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364 | [3]: http://highlightjs.readthedocs.io/en/latest/api.html#highlightblock-block
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365 | [4]: http://highlightjs.readthedocs.io/en/latest/api.html#configure-options
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366 | [5]: https://highlightjs.org/download/
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367 | [6]: http://highlightjs.readthedocs.io/en/latest/building-testing.html
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368 | [7]: https://github.com/highlightjs/highlight.js/blob/main/LICENSE
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369 | [8]: https://github.com/highlightjs/highlight.js/blob/main/CONTRIBUTORS.md
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370 | [9]: https://github.com/highlightjs/highlight.js/blob/main/SUPPORTED_LANGUAGES.md
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371 | [10]: https://github.com/highlightjs/
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