If vs. while in specific JavaScript code

Question

Why does the author of Test-Driven JavaScript Development (Christian Johansen) use the while statement instead of the if statement in the code below?

function getEventTarget(event) {
    var target = event.target || event.srcElement;

    while (target && target.nodeType != 1) {
        target = target.parentNode;
    }

    return target;
}

You do realize that while is a loop, right? It will execute over and over until the condition becomes false. — Gabe
– Gabe, Commented Feb 24, 2012 at 4:34

Phrogz · Accepted Answer · 2012-02-24 04:31:57Z

9

Because the author wanted to keep walking up the tree until the correct node type was found; it might not be the immediate parent.

However, in this case it makes no sense, as parentNode will always return an element in real-world usage (or a Document).

answered Feb 24, 2012 at 4:31

Phrogz

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Comments

Hector Sanchez · Accepted Answer · 2012-02-24 04:46:15Z

0

Because he is walking up..

If you see pretty well, in the loop he is assigning the target again with its parent and the parent is not nodetype 1

 target = target.parentNode;

I don't know what is he trying or what is the purpose or the goal but it's quite simple..

Imagine the DOM

<div>
  <div>
     <div>
        <div>
           Imagine he starts from here.. he will always get the max parent with not nodetype 1 the hightes parent so the first div..
         </div>
     </div>
  </div>
</div>

SO basically. He is getting the Higher parent ... That's why is he looping.. if uses the If.. he will get just the First parent

edited Feb 24, 2012 at 4:46

answered Feb 24, 2012 at 4:38

Hector Sanchez

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3 Comments

Phrogz Over a year ago

But nodeType==1 is an element node, so as soon as you walk out of the TextNode (in the unlikely case that it fired the event) you have an element.

Phrogz Over a year ago

It keeps walking as long as nodeType!=1, which means that it stops as soon as nodeType==1, which it will always do either immediately or after one iteration.

Hector Sanchez Over a year ago

Yes my mystake, you are right, BUT i think he did it for something look at this example javascriptkit.com/domref/nodetype.shtml

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