Accessing nested JavaScript objects and arrays by string path

by

I just made this based on some similar code I already had, it appears to work:

Object.byString = function(o, s) {
    s = s.replace(/\[(\w+)\]/g, '.$1'); // convert indexes to properties
    s = s.replace(/^\./, '');           // strip a leading dot
    var a = s.split('.');
    for (var i = 0, n = a.length; i < n; ++i) {
        var k = a[i];
        if (k in o) {
            o = o[k];
        } else {
            return;
        }
    }
    return o;
}

Usage::

Object.byString(someObj, 'part3[0].name');

See a working demo at http://jsfiddle.net/alnitak/hEsys/

EDIT some have noticed that this code will throw an error if passed a string where the left-most indexes don’t correspond to a correctly nested entry within the object. This is a valid concern, but IMHO best addressed with a try / catch block when calling, rather than having this function silently return undefined for an invalid index.

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