Convert JavaScript string in dot notation into an object reference

Question

Given a JS object

var obj = { a: { b: \'1\', c: \'2\' } }

and a string

\"a.b\"

how can I convert the stri

Answer 1

At the risk of beating a dead horse... I find this most useful in traversing nested objects to reference where you're at with respect to the base object or to a similar object with the same structure. To that end, this is useful with a nested object traversal function. Note that I've used an array to hold the path. It would be trivial to modify this to use either a string path or an array. Also note that you can assign "undefined" to the value, unlike some of the other implementations.

/*
 * Traverse each key in a nested object and call fn(curObject, key, value, baseObject, path)
 * on each. The path is an array of the keys required to get to curObject from
 * baseObject using objectPath(). If the call to fn() returns falsey, objects below
 * curObject are not traversed. Should be called as objectTaverse(baseObject, fn).
 * The third and fourth arguments are only used by recursion.
 */
function objectTraverse (o, fn, base, path) {
    path = path || [];
    base = base || o;
    Object.keys(o).forEach(function (key) {
        if (fn(o, key, o[key], base, path) && jQuery.isPlainObject(o[key])) {
            path.push(key);
            objectTraverse(o[key], fn, base, path);
            path.pop();
        }
    });
}

/*
 * Get/set a nested key in an object. Path is an array of the keys to reference each level
 * of nesting. If value is provided, the nested key is set.
 * The value of the nested key is returned.
 */
function objectPath (o, path, value) {
    var last = path.pop();

    while (path.length && o) {
        o = o[path.shift()];
    }
    if (arguments.length < 3) {
        return (o? o[last] : o);
    }
    return (o[last] = value);
}