Rails has a "try" method for all objects. Is there a way to do something similar in Javascript?

Question

Because null and undefined are not objects in JavaScript, I guess it could be a global helper function?

Example usage could be something like:

var a = { b: { c: { d: 'hello world!' } } };
tryPath(a, 'b', 'c', 'd'); // returns 'hello world!'
tryPath(a, 'x', 'c', 'd'); // returns undefined

Answer 1

You can even shorten it with Array.prototype.reduce, like this

function tryPath(object) {
    var path = Array.prototype.slice.call(arguments, 1);
    if (!path.length) return undefined;
    return path.reduce(function(result, current) {
        return result === undefined ? result : result[current];
    }, object);
}

var a = { b: { c: { d: 'hello world!' } } };
console.assert(tryPath(a, 'b', 'c', 'd') === 'hello world!');
console.assert(tryPath(a, 'x', 'c', 'd') === undefined);
console.assert(tryPath(a) === undefined);

Answer 2

You can do something fairly simple without a helper function:

var a = { b: { c: { d: 'hello world!' } } };
a && a.b && a.b.c && a.b.c.d; // returns 'hello world!'
a && a.x && a.x.c && a.x.c.d; // returns undefined

Answer 3

var tryPath = function tryPath() {
    if (arguments.length < 2) {
        return undefined; // Not valid
    } else {
        var object = arguments[0];
        for (var i = 1; i < arguments.length; i++) {
            if (object !== null && typeof object === 'object') {
                object = object[arguments[i]];
            } else {
                return undefined;
            }
        }
        return object;
    }
};