ljharb
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 ] }methods
Each method that takes an fn uses the context documented below in the context
section.
.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.
.get(path)
Get the element at the array path.
.set(path, value)
Set the element at the array path to value.
.has(path)
Return whether the element at the array path exists.
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.
install
Using npm do:
$ npm install traverselicense
MIT