Question

I’m getting some odd behaviour when trying to use setInterval within an object.

Here is my code:

var Person = {
    speech: null,

    tryToSpeak: function ()
    {
        this.speech = "hello";
        self.setTimeout (this.speak, 1000);
    },

    speak: function ()
    {
        // prints out undefined
        console.log (this.speech);
    }
}

Person.tryToSpeak ();

When speak() is run via setTimeout() it doesn’t have access to any of the objects data such as speech. What the hell is going on? Is this unavoidable behaviour?

Answer 1

The methods don’t carry the object information with them. You can use .bind to …bind the method to an object:

window.setTimeout(this.speak.bind( this ), 1000);

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