Javascript using this in a function

Question

UPDATE: .call function works, thanks for the quick replies :) Tested the other solution suggested too and

So I have this code, function setAttribute which takes four inputs and then applies them using this. The long code where it does

this.setAttribute("data-index-all", 1); works, but when I made it into a function it doesn't. I'm pretty sure that the problem is with "this" in a function. If someone could point out what's wrong I'd be very thankful.

function setAttribute(a, b, c, d){
this.setAttribute("data-index-all", a);
this.setAttribute("data-index-uleval", b);
this.setAttribute("data-index-vasakul", c);
this.setAttribute("data-index-paremal", d);
}    

if (!flipped) {
            setAttribute(1, 0, 1, 0);
        }else{
            setAttribute(0, 1, 0, 1);
        }


if (!flipped) {
                    this.setAttribute("data-index-all", 1);
                    this.setAttribute("data-index-uleval", 0);
                    this.setAttribute("data-index-vasakul", 1);
                    this.setAttribute("data-index-paremal", 0);
                } else {
                    this.setAttribute("data-index-all", 0);
                    this.setAttribute("data-index-uleval", 1);
                    this.setAttribute("data-index-vasakul", 0);
                    this.setAttribute("data-index-paremal", 1);
                }

javascript already has setAttribute so define another function name... — Bhojendra Rauniyar
– Bhojendra Rauniyar, Commented Mar 31, 2015 at 8:19

Arun P Johny · Accepted Answer · 2015-03-31 08:20:37Z

2

When you call a function without a context, this inside the function will refer to the global object(window).

You can use .call() to pass a custom context

function setAttribute(a, b, c, d) {
    this.setAttribute("data-index-all", a);
    this.setAttribute("data-index-uleval", b);
    this.setAttribute("data-index-vasakul", c);
    this.setAttribute("data-index-paremal", d);
}

if (!flipped) {
    setAttribute.call(this, 1, 0, 1, 0);
} else {
    setAttribute.call(this, 0, 1, 0, 1);
}

But in your scenario using @codehx answer will be best

answered Mar 31, 2015 at 8:20

Arun P Johny

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dsharew · Accepted Answer · 2015-03-31 09:34:08Z

2

try passing the element to which this refers to as the function argument.

function setAttribute(element, a, b, c, d){
  element.setAttribute("data-index-all", a);
  element.setAttribute("data-index-uleval", b);
  element.setAttribute("data-index-vasakul", c);
  element.setAttribute("data-index-paremal", d);
}

edited Mar 31, 2015 at 9:34

answered Mar 31, 2015 at 8:20

dsharew

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