Apply/Call method in [removed] What is the first arguments “this”?

Question

I am confused about using apply or call method correctly. I know that apply is passing an array to the function and call is passing strings to a function. For example the code b

Answer 1

It's the context for the function. If you have this.something inside the function, it will access that particular property from that context object.

    

    function foo(bar) {
        this.bar = bar;
    }
    
    foo.apply(this, ['Hello']);    //calling foo using window as context (this = window in global context in browser)
    console.log(this.bar);         //as you can see window.bar is the same as this.bar
    console.log(window.bar);
    
    var ctx = {};    //create a new context
    
    foo.apply(ctx, ['Good night']);
    console.log(ctx.bar);        //ctx now has bar property that is injected from foo function

Open up your dev console to see result.

See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply