source: trip-planner-front/node_modules/estraverse/README.md@ 6a3a178

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1### Estraverse [![Build Status](https://secure.travis-ci.org/estools/estraverse.svg)](http://travis-ci.org/estools/estraverse)
2
3Estraverse ([estraverse](http://github.com/estools/estraverse)) is
4[ECMAScript](http://www.ecma-international.org/publications/standards/Ecma-262.htm)
5traversal functions from [esmangle project](http://github.com/estools/esmangle).
6
7### Documentation
8
9You can find usage docs at [wiki page](https://github.com/estools/estraverse/wiki/Usage).
10
11### Example Usage
12
13The following code will output all variables declared at the root of a file.
14
15```javascript
16estraverse.traverse(ast, {
17 enter: function (node, parent) {
18 if (node.type == 'FunctionExpression' || node.type == 'FunctionDeclaration')
19 return estraverse.VisitorOption.Skip;
20 },
21 leave: function (node, parent) {
22 if (node.type == 'VariableDeclarator')
23 console.log(node.id.name);
24 }
25});
26```
27
28We can use `this.skip`, `this.remove` and `this.break` functions instead of using Skip, Remove and Break.
29
30```javascript
31estraverse.traverse(ast, {
32 enter: function (node) {
33 this.break();
34 }
35});
36```
37
38And estraverse provides `estraverse.replace` function. When returning node from `enter`/`leave`, current node is replaced with it.
39
40```javascript
41result = estraverse.replace(tree, {
42 enter: function (node) {
43 // Replace it with replaced.
44 if (node.type === 'Literal')
45 return replaced;
46 }
47});
48```
49
50By passing `visitor.keys` mapping, we can extend estraverse traversing functionality.
51
52```javascript
53// This tree contains a user-defined `TestExpression` node.
54var tree = {
55 type: 'TestExpression',
56
57 // This 'argument' is the property containing the other **node**.
58 argument: {
59 type: 'Literal',
60 value: 20
61 },
62
63 // This 'extended' is the property not containing the other **node**.
64 extended: true
65};
66estraverse.traverse(tree, {
67 enter: function (node) { },
68
69 // Extending the existing traversing rules.
70 keys: {
71 // TargetNodeName: [ 'keys', 'containing', 'the', 'other', '**node**' ]
72 TestExpression: ['argument']
73 }
74});
75```
76
77By passing `visitor.fallback` option, we can control the behavior when encountering unknown nodes.
78
79```javascript
80// This tree contains a user-defined `TestExpression` node.
81var tree = {
82 type: 'TestExpression',
83
84 // This 'argument' is the property containing the other **node**.
85 argument: {
86 type: 'Literal',
87 value: 20
88 },
89
90 // This 'extended' is the property not containing the other **node**.
91 extended: true
92};
93estraverse.traverse(tree, {
94 enter: function (node) { },
95
96 // Iterating the child **nodes** of unknown nodes.
97 fallback: 'iteration'
98});
99```
100
101When `visitor.fallback` is a function, we can determine which keys to visit on each node.
102
103```javascript
104// This tree contains a user-defined `TestExpression` node.
105var tree = {
106 type: 'TestExpression',
107
108 // This 'argument' is the property containing the other **node**.
109 argument: {
110 type: 'Literal',
111 value: 20
112 },
113
114 // This 'extended' is the property not containing the other **node**.
115 extended: true
116};
117estraverse.traverse(tree, {
118 enter: function (node) { },
119
120 // Skip the `argument` property of each node
121 fallback: function(node) {
122 return Object.keys(node).filter(function(key) {
123 return key !== 'argument';
124 });
125 }
126});
127```
128
129### License
130
131Copyright (C) 2012-2016 [Yusuke Suzuki](http://github.com/Constellation)
132 (twitter: [@Constellation](http://twitter.com/Constellation)) and other contributors.
133
134Redistribution and use in source and binary forms, with or without
135modification, are permitted provided that the following conditions are met:
136
137 * Redistributions of source code must retain the above copyright
138 notice, this list of conditions and the following disclaimer.
139
140 * Redistributions in binary form must reproduce the above copyright
141 notice, this list of conditions and the following disclaimer in the
142 documentation and/or other materials provided with the distribution.
143
144THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
145AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
146IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
147ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
148DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
149(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
150LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
151ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
152(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
153THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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