How to set object property (of object property of..) given its string name in JavaScript?

Question

Suppose we are only given

var obj = {};
var propName = \"foo.bar.foobar\";

How can we set the prop

Answer 1

Object.getPath = 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;
};

Object.setPath = function(o, p, v) {
    var a = p.split('.');
    var o = o;
    for (var i = 0; i < a.length - 1; i++) {
        if (a[i].indexOf('[') === -1) {
            var n = a[i];
            if (n in o) {
                o = o[n];
            } else {
                o[n] = {};
                o = o[n];
            }
        } else {
            // Not totaly optimised
            var ix = a[i].match(/\[.*?\]/g)[0];
            var n = a[i].replace(ix, '');
            o = o[n][ix.substr(1,ix.length-2)]
        }
    }

    if (a[a.length - 1].indexOf('[') === -1) {
        o[a[a.length - 1]] = v;
    } else {
        var ix = a[a.length - 1].match(/\[.*?\]/g)[0];
        var n = a[a.length - 1].replace(ix, '');
        o[n][ix.substr(1,ix.length-2)] = v;
    }
};