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

edit: I've created a jsPerf.com testcase to compare the accepted answer with my version. Turns out that my version is faster, especially when you go very deep.

http://jsfiddle.net/9YMm8/

var nestedObjectAssignmentFor = function(obj, propString, value) {
    var propNames = propString.split('.'),
        propLength = propNames.length-1,
        tmpObj = obj;

    for (var i = 0; i <= propLength ; i++) {
        tmpObj = tmpObj[propNames[i]] = i !== propLength ?  {} : value;  
    }
    return obj;
}

var obj = nestedObjectAssignment({},"foo.bar.foobar","hello world");

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