Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Traverse and transform objects by visiting every node on a recursive walk.
branch: master

This branch is 32 commits behind substack:master

Fetching latest commit…

Cannot retrieve the latest commit at this time

Failed to load latest commit information.
examples
test
LICENSE
README.markdown
index.js
package.json

README.markdown

traverse

Traverse and transform objects by visiting every node on a recursive walk.

examples

transform negative numbers in-place

negative.js

var traverse = require('traverse');
var obj = [ 5, 6, -3, [ 7, 8, -2, 1 ], { f : 10, g : -13 } ];

traverse(obj).forEach(function (x) {
    if (x < 0) this.update(x + 128);
});

console.dir(obj);

Output:

[ 5, 6, 125, [ 7, 8, 126, 1 ], { f: 10, g: 115 } ]

collect leaf nodes

leaves.js

var traverse = require('traverse');

var obj = {
    a : [1,2,3],
    b : 4,
    c : [5,6],
    d : { e : [7,8], f : 9 },
};

var leaves = traverse(obj).reduce(function (acc, x) {
    if (this.isLeaf) acc.push(x);
    return acc;
}, []);

console.dir(leaves);

Output:

[ 1, 2, 3, 4, 5, 6, 7, 8, 9 ]

scrub circular references

scrub.js:

var traverse = require('traverse');

var obj = { a : 1, b : 2, c : [ 3, 4 ] };
obj.c.push(obj);

var scrubbed = traverse(obj).map(function (x) {
    if (this.circular) this.remove()
});
console.dir(scrubbed);

output:

{ a: 1, b: 2, c: [ 3, 4 ] }

context

Each method that takes a callback has a context (its this object) with these attributes:

this.node

The present node on the recursive walk

this.path

An array of string keys from the root to the present node

this.parent

The context of the node's parent. This is undefined for the root node.

this.key

The name of the key of the present node in its parent. This is undefined for the root node.

this.isRoot, this.notRoot

Whether the present node is the root node

this.isLeaf, this.notLeaf

Whether or not the present node is a leaf node (has no children)

this.level

Depth of the node within the traversal

this.circular

If the node equals one of its parents, the circular attribute is set to the context of that parent and the traversal progresses no deeper.

this.update(value, stopHere=false)

Set a new value for the present node.

All the elements in value will be recursively traversed unless stopHere is true.

this.remove(stopHere=false)

Remove the current element from the output. If the node is in an Array it will be spliced off. Otherwise it will be deleted from its parent.

this.delete(stopHere=false)

Delete the current element from its parent in the output. Calls delete even on Arrays.

this.before(fn)

Call this function before any of the children are traversed.

You can assign into this.keys here to traverse in a custom order.

this.after(fn)

Call this function after any of the children are traversed.

this.pre(fn)

Call this function before each of the children are traversed.

this.post(fn)

Call this function after each of the children are traversed.

methods

.map(fn)

Execute fn for each node in the object and return a new object with the results of the walk. To update nodes in the result use this.update(value).

.forEach(fn)

Execute fn for each node in the object but unlike .map(), when this.update() is called it updates the object in-place.

.reduce(fn, acc)

For each node in the object, perform a left-fold with the return value of fn(acc, node).

If acc isn't specified, acc is set to the root object for the first step and the root element is skipped.

.paths()

Return an Array of every possible non-cyclic path in the object. Paths are Arrays of string keys.

.nodes()

Return an Array of every node in the object.

.clone()

Create a deep clone of the object.

install

Using npm do:

$ npm install traverse

test

Using expresso do:

$ expresso

100% wahoo, your stuff is not broken!

in the browser

Use browserify to run traverse in the browser.

traverse has been tested and works with:

  • Internet Explorer 5.5, 6.0, 7.0, 8.0, 9.0
  • Firefox 3.5
  • Chrome 6.0
  • Opera 10.6
  • Safari 5.0
Something went wrong with that request. Please try again.