Estraverse 
Estraverse (estraverse) is ECMAScript traversal functions from esmangle project.
Documentation
You can find usage docs at wiki page.
Example Usage
The following code will output all variables declared at the root of a file.
estraverse.traverse(ast, {
enter: function (node, parent) {
if (node.type == 'FunctionExpression' || node.type == 'FunctionDeclaration')
return estraverse.VisitorOption.Skip;
},
leave: function (node, parent) {
if (node.type == 'VariableDeclarator')
console.log(node.id.name);
}
});
We can use this.skip, this.remove and this.break functions instead of using Skip, Remove and Break.
estraverse.traverse(ast, {
enter: function (node) {
this.break();
}
});
And estraverse provides estraverse.replace function. When returning node from enter/leave, current node is replaced with it.
result = estraverse.replace(tree, {
enter: function (node) {
// Replace it with replaced.
if (node.type === 'Literal')
return replaced;
}
});
By passing visitor.keys mapping, we can extend estraverse traversing functionality.
// This tree contains a user-defined `TestExpression` node.
var tree = {
type: 'TestExpression',
// This 'argument' is the property containing the other **node**.
argument: {
type: 'Literal',
value: 20
},
// This 'extended' is the property not containing the other **node**.
extended: true
};
estraverse.traverse(tree, {
enter: function (node) { },
// Extending the existing traversing rules.
keys: {
// TargetNodeName: [ 'keys', 'containing', 'the', 'other', '**node**' ]
TestExpression: ['argument']
}
});
By passing visitor.fallback option, we can control the behavior when encountering unknown nodes.
// This tree contains a user-defined `TestExpression` node.
var tree = {
type: 'TestExpression',
// This 'argument' is the property containing the other **node**.
argument: {
type: 'Literal',
value: 20
},
// This 'extended' is the property not containing the other **node**.
extended: true
};
estraverse.traverse(tree, {
enter: function (node) { },
// Iterating the child **nodes** of unknown nodes.
fallback: 'iteration'
});
License
Copyright (C) 2012-2013 Yusuke Suzuki (twitter: @Constellation) and other contributors.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL