How to mock localStorage in JavaScript unit tests?

Question

Are there any libraries out there to mock localStorage?

I\'ve been using Sinon.JS for most of my other javascript mocking and have found it is really gr

Answer 1

Are there any libraries out there to mock localStorage?

I just wrote one:

(function () {
    var localStorage = {};
    localStorage.setItem = function (key, val) {
         this[key] = val + '';
    }
    localStorage.getItem = function (key) {
        return this[key];
    }
    Object.defineProperty(localStorage, 'length', {
        get: function () { return Object.keys(this).length - 2; }
    });

    // Your tests here

})();

My initial testing shows that localStorage refuses to be assignable in firefox

Only in global context. With a wrapper function as above, it works just fine.