1 | # big.js
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2 |
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3 | **A small, fast JavaScript library for arbitrary-precision decimal arithmetic.**
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4 |
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5 | The little sister to [bignumber.js](https://github.com/MikeMcl/bignumber.js/) and [decimal.js](https://github.com/MikeMcl/decimal.js/). See [here](https://github.com/MikeMcl/big.js/wiki) for some notes on the difference between them.
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6 |
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7 | ## Features
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8 |
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9 | - Faster, smaller and easier-to-use than JavaScript versions of Java's BigDecimal
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10 | - Only 5.9 KB minified and 2.7 KB gzipped
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11 | - Simple API
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12 | - Replicates the `toExponential`, `toFixed` and `toPrecision` methods of JavaScript's Number type
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13 | - Includes a `sqrt` method
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14 | - Stores values in an accessible decimal floating point format
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15 | - No dependencies
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16 | - Comprehensive [documentation](http://mikemcl.github.io/big.js/) and test set
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17 |
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18 | ## Set up
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19 |
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20 | The library is the single JavaScript file *big.js* (or *big.min.js*, which is *big.js* minified).
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21 |
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22 | Browser:
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23 |
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24 | ```html
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25 | <script src='path/to/big.js'></script>
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26 | ```
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27 |
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28 | [Node.js](http://nodejs.org):
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29 |
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30 | ```bash
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31 | $ npm install big.js
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32 | ```
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33 |
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34 | ```javascript
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35 | const Big = require('big.js');
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36 | ```
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37 |
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38 | ES6 module:
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39 |
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40 | ```javascript
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41 | import Big from 'big.mjs';
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42 | ```
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43 | ## Use
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44 |
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45 | *In all examples below, `var`, semicolons and `toString` calls are not shown. If a commented-out value is in quotes it means `toString` has been called on the preceding expression.*
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46 |
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47 | The library exports a single function, `Big`, the constructor of Big number instances.
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48 | It accepts a value of type number, string or Big number object.
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49 |
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50 | x = new Big(123.4567)
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51 | y = Big('123456.7e-3') // 'new' is optional
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52 | z = new Big(x)
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53 | x.eq(y) && x.eq(z) && y.eq(z) // true
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54 |
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55 | A Big number is immutable in the sense that it is not changed by its methods.
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56 |
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57 | 0.3 - 0.1 // 0.19999999999999998
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58 | x = new Big(0.3)
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59 | x.minus(0.1) // "0.2"
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60 | x // "0.3"
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61 |
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62 | The methods that return a Big number can be chained.
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63 |
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64 | x.div(y).plus(z).times(9).minus('1.234567801234567e+8').plus(976.54321).div('2598.11772')
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65 | x.sqrt().div(y).pow(3).gt(y.mod(z)) // true
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66 |
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67 | Like JavaScript's Number type, there are `toExponential`, `toFixed` and `toPrecision` methods.
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68 |
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69 | x = new Big(255.5)
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70 | x.toExponential(5) // "2.55500e+2"
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71 | x.toFixed(5) // "255.50000"
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72 | x.toPrecision(5) // "255.50"
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73 |
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74 | The arithmetic methods always return the exact result except `div`, `sqrt` and `pow`
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75 | (with negative exponent), as these methods involve division.
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76 |
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77 | The maximum number of decimal places and the rounding mode used to round the results of these methods is determined by the value of the `DP` and `RM` properties of the `Big` number constructor.
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78 |
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79 | Big.DP = 10
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80 | Big.RM = 1
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81 |
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82 | x = new Big(2);
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83 | y = new Big(3);
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84 | z = x.div(y) // "0.6666666667"
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85 | z.sqrt() // "0.8164965809"
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86 | z.pow(-3) // "3.3749999995"
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87 | z.times(z) // "0.44444444448888888889"
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88 | z.times(z).round(10) // "0.4444444445"
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89 |
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90 | Multiple Big number constructors can be created, each with an independent configuration.
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91 |
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92 | The value of a Big number is stored in a decimal floating point format in terms of a coefficient, exponent and sign.
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93 |
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94 | x = new Big(-123.456);
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95 | x.c // [1,2,3,4,5,6] coefficient (i.e. significand)
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96 | x.e // 2 exponent
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97 | x.s // -1 sign
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98 |
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99 | For further information see the [API](http://mikemcl.github.io/big.js/) reference from the *doc* folder.
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100 |
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101 | ## Test
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102 |
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103 | The *test* directory contains the test scripts for each Big number method.
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104 |
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105 | The tests can be run with Node.js or a browser.
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106 |
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107 | To run all the tests
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108 |
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109 | $ npm test
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110 |
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111 | To test a single method
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112 |
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113 | $ node test/toFixed
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114 |
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115 | For the browser, see *single-test.html* and *every-test.html* in the *test/browser* directory.
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116 |
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117 | *big-vs-number.html* is a simple application that enables some of the methods of big.js to be compared with those of JavaScript's Number type.
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118 |
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119 | ## Performance
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120 |
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121 | The *perf* directory contains two legacy applications and a *lib* directory containing the BigDecimal libraries used by both.
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122 |
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123 | *big-vs-bigdecimal.html* tests the performance of big.js against the JavaScript translations of two versions of BigDecimal, its use should be more or less self-explanatory.
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124 |
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125 | * [GWT: java.math.BigDecimal](https://github.com/iriscouch/bigdecimal.js)
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126 | * [ICU4J: com.ibm.icu.math.BigDecimal](https://github.com/dtrebbien/BigDecimal.js)
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127 |
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128 | The BigDecimal in the npm registry is the GWT version. It has some bugs, see the Node.js script *perf/lib/bigdecimal_GWT/bugs.js* for examples of flaws in its *remainder*, *divide* and *compareTo* methods.
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129 |
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130 | *bigtime.js* is a Node.js command-line application which tests the performance of big.js against the GWT version of
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131 | BigDecimal from the npm registry.
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132 |
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133 | For example, to compare the time taken by the big.js `plus` method and the BigDecimal `add` method
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134 |
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135 | $ node bigtime plus 10000 40
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136 |
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137 | This will time 10000 calls to each, using operands of up to 40 random digits and will check that the results match.
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138 |
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139 | For help
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140 |
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141 | $ node bigtime -h
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142 |
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143 | ## Build
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144 |
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145 | If [uglify-js](https://github.com/mishoo/UglifyJS2) is installed globally
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146 |
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147 | $ npm install uglify-js -g
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148 |
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149 | then
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150 |
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151 | $ npm run build
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152 |
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153 | will create *big.min.js*.
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154 |
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155 | ## TypeScript
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156 |
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157 | The [DefinitelyTyped](https://github.com/borisyankov/DefinitelyTyped) project has a Typescript type definitions file for big.js.
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158 |
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159 | $ npm install @types/big.js
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160 |
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161 | Any questions about the TypeScript type definitions file should be addressed to the DefinitelyTyped project.
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162 |
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163 | ## Feedback
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164 |
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165 | Bugs/comments/questions?
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166 |
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167 | Open an issue, or email <a href="mailto:M8ch88l@gmail.com">Michael</a>
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168 |
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169 | ## Licence
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170 |
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171 | [MIT](LICENCE)
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172 |
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173 | ## Contributors
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174 |
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175 | This project exists thanks to all the people who contribute. [[Contribute](CONTRIBUTING.md)].
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176 | <a href="graphs/contributors"><img src="https://opencollective.com/bigjs/contributors.svg?width=890&button=false" /></a>
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177 |
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178 |
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179 | ## Backers
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180 |
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181 | Thank you to all our backers! 🙏 [[Become a backer](https://opencollective.com/bigjs#backer)]
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182 |
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183 | <a href="https://opencollective.com/bigjs#backers" target="_blank"><img src="https://opencollective.com/bigjs/backers.svg?width=890"></a>
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184 |
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185 |
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186 | ## Sponsors
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187 |
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188 | Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [[Become a sponsor](https://opencollective.com/bigjs#sponsor)]
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189 |
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190 | <a href="https://opencollective.com/bigjs/sponsor/0/website" target="_blank"><img src="https://opencollective.com/bigjs/sponsor/0/avatar.svg"></a>
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191 | <a href="https://opencollective.com/bigjs/sponsor/1/website" target="_blank"><img src="https://opencollective.com/bigjs/sponsor/1/avatar.svg"></a>
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192 | <a href="https://opencollective.com/bigjs/sponsor/2/website" target="_blank"><img src="https://opencollective.com/bigjs/sponsor/2/avatar.svg"></a>
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193 | <a href="https://opencollective.com/bigjs/sponsor/3/website" target="_blank"><img src="https://opencollective.com/bigjs/sponsor/3/avatar.svg"></a>
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194 | <a href="https://opencollective.com/bigjs/sponsor/4/website" target="_blank"><img src="https://opencollective.com/bigjs/sponsor/4/avatar.svg"></a>
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200 |
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201 |
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