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traverse ======== Traverse and transform objects by visiting every node on a recursive walk. examples ======== transform negative numbers in-place ----------------------------------- negative.js ````javascript 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 ````javascript 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 ] 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) ------------------ Set a new value for the present node. this.remove() ------------- 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() ------------- 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. 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](http://en.wikipedia.org/wiki/Fold_(higher-order_function)) 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. .deepEqual(obj) --------------- Returns a boolean, whether the instance value is equal to the supplied object along a deep traversal using some opinionated choices. Some notes: * RegExps are equal if their .toString()s match, but not functions since functions can close over different variables. * Date instances are compared using `.getTime()` just like `assert.deepEqual()`. * Circular references must refer to the same paths within the data structure for both objects. For instance, in this snippet: ````javascript var a = [1]; a.push(a); // a = [ 1, *a ] var b = [1]; b.push(a); // b = [ 1, [ 1, *a ] ] ```` `a` is not the same as `b` since even though the expansion is the same, the circular references in each refer to different paths into the data structure. However, in: ````javascript var c = [1]; c.push(c); // c = [ 1, *c ]; ```` `c` is equal to `a` in a `deepEqual()` because they have the same terminal node structure. * Arguments objects are not arrays and neither are they the same as regular objects. * Instances created with `new` of String, Boolean, and Number types are never equal to the native versions. .paths() -------- Return an `Array` of every possible non-cyclic path in the object. Paths are `Array`s of string keys. .nodes() -------- Return an `Array` of every node in the object. .clone() -------- Create a deep clone of the object. installation ============ Using npm: npm install traverse Or check out the repository and link your development copy: git clone http://github.com/substack/js-traverse.git cd js-traverse npm link . You can test traverse with "expresso":http://github.com/visionmedia/expresso (`npm install expresso`): js-traverse $ expresso 100% wahoo, your stuff is not broken! hash transforms =============== This library formerly had a hash transformation component. It has been [moved to the hashish package](https://github.com/substack/node-hashish).