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Clone AST without extra properties
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estools/espurify
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Clone AST without extra properties
Returns new clone oforiginalAst but without extra properties.
Leaves properties defined inThe ESTree Spec (formerly known asMozilla SpiderMonkey Parser API) only. Also note that extra informations (such asloc,range andraw) are eliminated too.
(note: usingespurify as a default exported function is deprecated in favor of named exports aiming ESM era, and will be removed in future major releases)
Returns customized function for cloning AST, with user-providedallowList.
(note:espurify.cloneWithWhitelist is still exported but deprecated in favor of more inclusive language and will be removed in future major releases)
Returns new clone oforiginalAst by customized function.
| type | default value |
|---|---|
object | N/A |
allowList is an object containing NodeType as keys and properties as values.
{ArrayExpression:['type','elements'],ArrayPattern:['type','elements'],ArrowFunctionExpression:['type','id','params','body','generator','expression'],AssignmentExpression:['type','operator','left','right'], ...
Returns customized function for cloning AST, configured by customoptions.
Returns new clone oforiginalAst by customized function.
| type | default value |
|---|---|
object | {} |
Configuration options. If not passed, default options will be used.
| type | default value |
|---|---|
string ornumber | 2025 |
Indicates the ECMAScript version to clone. Must be either 5, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025.
| type | default value |
|---|---|
array ofstring | null |
List of extra properties to be left in result AST. For example, functions returned byespurify.customize({extra: ['raw']}) will preserveraw properties ofLiteral. Functions return byespurify.customize({extra: ['loc', 'range']}) will preserveloc andrange properties of each Node.
constespurify=require('espurify');constestraverse=require('estraverse');constacorn=require('acorn');constsyntax=estraverse.Syntax;constassert=require('assert');constjsCode='assert("foo")';// Adding extra informations to ASTconstoriginalAst=acorn.parse(jsCode,{locations:true,ranges:true,ecmaVersion:2022});estraverse.replace(originalAst,{leave:function(currentNode,parentNode){if(currentNode.type===syntax.Literal&&typeofcurrentNode.raw!=='undefined'){currentNode['x-verbatim-bar']={content :currentNode.raw,precedence :18// escodegen.Precedence.Primary};returncurrentNode;}else{returnundefined;}}});// purify ASTconstpurifiedClone=espurify.purifyAst(originalAst);// Extra properties are eliminated from cloned ASTassert.deepEqual(purifiedClone,{type:'Program',body:[{type:'ExpressionStatement',expression:{type:'CallExpression',callee:{type:'Identifier',name:'assert'},arguments:[{type:'Literal',value:'foo'}],optional:false}}],sourceType:'script'});// original AST is not modifiedassert.deepEqual(originalAst,{type:'Program',start:0,end:13,loc:{start:{line:1,column:0},end:{line:1,column:13}},range:[0,13],body:[{type:'ExpressionStatement',start:0,end:13,loc:{start:{line:1,column:0},end:{line:1,column:13}},range:[0,13],expression:{type:'CallExpression',start:0,end:13,loc:{start:{line:1,column:0},end:{line:1,column:13}},range:[0,13],callee:{type:'Identifier',start:0,end:6,loc:{start:{line:1,column:0},end:{line:1,column:6}},range:[0,6],name:'assert'},arguments:[{type:'Literal',start:7,end:12,loc:{start:{line:1,column:7},end:{line:1,column:12}},range:[7,12],value:'foo',raw:'"foo"',"x-verbatim-bar":{content:'"foo"',precedence:18}}],optional:false}}],sourceType:'script'});
Install
$ npm install --save espurifyUse
constespurify=require('espurify');
Licensed under theMIT license.
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Clone AST without extra properties