Dynamic deep setting for a JavaScript object [duplicate]

Question

Given a string for a object property path, how do I set this property dynamically.

Given this sample object:

var obj = {     a: {         b: [ { c: 'Before' } ]     } }; 

It should be able to set the value with a helper function like this:

setToValue(obj, 'After', 'a.b.0.c'); 

I tried it with the following code. But parent is a copy if the variable not a reference.

function setToValue(obj, value, path) {     var arrPath = path.split('.'),         parent = obj;      for (var i = 0, max = arrPath.length; i < max; i++) {         parent = parent[arrPath[i]];     }      parent = value; } 

Answer 1

a) What's wrong with a simple a.b[0].c = 'After'?

As for the method:

function setToValue(obj, value, path) {     var i;     path = path.split('.');     for (i = 0; i < path.length - 1; i++)         obj = obj[path[i]];      obj[path[i]] = value; } 

Here the JSFiddle: http://jsfiddle.net/QycBz/24/

Answer 2

Here is a full solution.

Also creates objects if they don't exist.

function setValue(obj, path, value) {   var a = path.split('.')   var o = obj   while (a.length - 1) {     var n = a.shift()     if (!(n in o)) o[n] = {}     o = o[n]   }   o[a[0]] = value }  function getValue(obj, path) {   path = path.replace(/\[(\w+)\]/g, '.$1')   path = path.replace(/^\./, '')   var a = path.split('.')   var o = obj   while (a.length) {     var n = a.shift()     if (!(n in o)) return     o = o[n]   }   return o }