Question

What is the best way to have js return undefined rather than throw an error when a parent property does not exist?

Example

a = {}
b = a.x.y.z
// Error: Cannot read property 'value' of undefined
// Target result: b = undefined

Answer 1

You have to check for the existence of each property:

var b;
if (a.x && a.x.y && a.x.y.z) {
    b = a.x.y.z
}

Or, simliar to another poster’s “safeGet” function:

var get = function (obj, ns) {
    var y = ns.split('.');
    for(var i = 0; i < y.length; i += 1) {
        if (obj[y[i]]) {
            obj = obj[y[i]];
        } else {
            return;
        }
    }
    return obj;
};

Use:

var b = get(a, 'x.y.z');