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espurify
================================
Clone new AST without extra properties
[![Build Status](https://travis-ci.org/estools/espurify.svg?branch=master)](https://travis-ci.org/estools/espurify)
[![NPM version](https://badge.fury.io/js/espurify.svg)](https://badge.fury.io/js/espurify)
[![License](https://img.shields.io/badge/license-MIT-brightgreen.svg)](https://github.com/estools/espurify/blob/master/MIT-LICENSE.txt)
[![Code Style](https://img.shields.io/badge/code%20style-semistandard-brightgreen.svg)](https://github.com/Flet/semistandard)
API
---------------------------------------
### var purifiedAstClone = espurify(originalAst)
Returns new clone of `originalAst` but without extra properties.
Leaves properties defined in [The ESTree Spec](https://github.com/estree/estree) (formerly known as [Mozilla SpiderMonkey Parser API](https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API)) only. Also note that extra informations (such as `loc`, `range` and `raw`) are eliminated too.
`espurify` supports [ES5](https://github.com/estree/estree/blob/master/es5.md), [ES2015](https://github.com/estree/estree/blob/master/es2015.md), and [ES2017](https://github.com/estree/estree/blob/master/es2017.md) properties.
### var customizedCloneFunctionWithWhiteList = espurify.cloneWithWhitelist(whiteList)
Returns customized function for cloning AST, with user-provided `whiteList`.
### var purifiedAstClone = customizedCloneFunctionWithWhiteList(originalAst)
Returns new clone of `originalAst` by customized function.
#### whiteList
| type | default value |
|:---------|:--------------|
| `object` | N/A |
`whiteList` is an object containing NodeType as keys and properties as values.
```js
{
ArrayExpression: ['type', 'elements'],
ArrayPattern: ['type', 'elements'],
ArrowFunctionExpression: ['type', 'id', 'params', 'body', 'generator', 'expression'],
AssignmentExpression: ['type', 'operator', 'left', 'right'],
...
```
### var customizedCloneFunction = espurify.customize(options)
Returns customized function for cloning AST, configured by custom `options`.
### var purifiedAstClone = customizedCloneFunction(originalAst)
Returns new clone of `originalAst` by customized function.
#### options
| type | default value |
|:---------|:--------------|
| `object` | `{}` |
Configuration options. If not passed, default options will be used.
#### options.extra
| type | default value |
|:--------------------|:--------------|
| `array` of `string` | null |
List of extra properties to be left in result AST. For example, functions returned by `espurify.customize({extra: ['raw']})` will preserve `raw` properties of `Literal`. Functions return by `espurify.customize({extra: ['loc', 'range']})` will preserve `loc` and `range` properties of each Node.
EXAMPLE
---------------------------------------
```javascript
var espurify = require('espurify'),
estraverse = require('estraverse'),
esprima = require('esprima'),
syntax = estraverse.Syntax,
assert = require('assert');
var jsCode = 'assert("foo")';
// Adding extra informations to AST
var originalAst = esprima.parse(jsCode, {tolerant: true, loc: true, raw: true});
estraverse.replace(originalAst, {
leave: function (currentNode, parentNode) {
if (currentNode.type === syntax.Literal && typeof currentNode.raw !== 'undefined') {
currentNode['x-verbatim-bar'] = {
content : currentNode.raw,
precedence : 18 // escodegen.Precedence.Primary
};
return currentNode;
} else {
return undefined;
}
}
});
// purify AST
var purifiedClone = espurify(originalAst);
// original AST is not modified
assert.deepEqual(originalAst, {
type: 'Program',
body: [
{
type: 'ExpressionStatement',
expression: {
type: 'CallExpression',
callee: {
type: 'Identifier',
name: 'assert',
loc: {
start: {
line: 1,
column: 0
},
end: {
line: 1,
column: 6
}
}
},
arguments: [
{
type: 'Literal',
value: 'foo',
raw: '"foo"',
loc: {
start: {
line: 1,
column: 7
},
end: {
line: 1,
column: 12
}
},
"x-verbatim-bar": {
content: '"foo"',
precedence: 18
}
}
],
loc: {
start: {
line: 1,
column: 0
},
end: {
line: 1,
column: 13
}
}
},
loc: {
start: {
line: 1,
column: 0
},
end: {
line: 1,
column: 13
}
}
}
],
loc: {
start: {
line: 1,
column: 0
},
end: {
line: 1,
column: 13
}
},
errors: []
});
// Extra properties are eliminated from cloned AST
assert.deepEqual(purifiedClone, {
type: 'Program',
body: [
{
type: 'ExpressionStatement',
expression: {
type: 'CallExpression',
callee: {
type: 'Identifier',
name: 'assert'
},
arguments: [
{
type: 'Literal',
value: 'foo'
}
]
}
}
]
});
```
INSTALL
---------------------------------------
### via npm
Install
$ npm install --save espurify
Use
```javascript
var espurify = require('espurify');
```
#### use espurify module on browser
`espurify` function is exported
<script type="text/javascript" src="./path/to/node_modules/espurify/build/espurify.js"></script>
### via bower
Install
$ bower install --save espurify
Load (`espurify` function is exported)
<script type="text/javascript" src="./path/to/bower_components/espurify/build/espurify.js"></script>
AUTHOR
---------------------------------------
* [Takuto Wada](https://github.com/twada)
LICENSE
---------------------------------------
Licensed under the [MIT](https://github.com/estools/espurify/blob/master/MIT-LICENSE.txt) license.