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 property obj.foo.bar.foobar to a certain value (say "hello world")? So I want to achieve this, while we only have the property name in a string:

obj.foo.bar.foobar = "hello world";

Answer 1

function assign(obj, prop, value) {
    if (typeof prop === "string")
        prop = prop.split(".");

    if (prop.length > 1) {
        var e = prop.shift();
        assign(obj[e] =
                 Object.prototype.toString.call(obj[e]) === "[object Object]"
                 ? obj[e]
                 : {},
               prop,
               value);
    } else
        obj[prop[0]] = value;
}

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

assign(obj, propName, "Value");