The time-complexity of using object as a dictionary in JavaScript

I am considering using JavaScript object as a dicti开发者_开发问答onary.

    var dict = {}
    dict['a'] = 1;
    dict['b'] = 2;

    var my_first = dict['a'];

I am not clear about the time-complexity of such implementation. Is it like hashing? Thank you.

JavaScript objects are often called "hashes" (mostly by recovering Perl addicts) or "hash tables" (unrepentant Java people). The typical look-up is somewhere between O(1) and O(log n).