Javascript setInterval and `this` solution

Question

I need to access this from my setInterval handler

prefs: null,
startup : function()
    {
        // init prefs
        ...
                


        

Answer 1

The default behavior of setInterval is to bind to the global context. You can call a member function by saving a copy of the current context. Inside retrieve_rate the this variable will be correctly bound to the original context. Here is what your code would look like:

var self = this;
this.intervalID = setInterval(
    function() { self.retrieve_rate(); },
    this.INTERVAL);

Bonus tip: For a plain function reference (as opposed to an object reference which has a member function) you can change the context by using JavaScript's call or apply methods.