CODEWITHSUNDEEP
javascript
heesub ahn
heesub ahn

Reputation: 27

I do not get the notion of stating a method or function in a variable

I am a javascript newbie, and faced a somewhat basic problem.

function expand(element){
 var target = document.getElementById(element);
 var h = target.offsetHeight;
 var sh = target.scrollHeight;
 var loopTimer = setTimeout('expand(\''+element+'\')',8);
 if(h < sh){
     h += 5;
 }  else {
     clearTimeout(loopTimer);
 }
 target.style.height = h+"px";
 }

In the code above, loopTimer variable is stated(setTimeout). However, what I am confused about is that it is simply 'stated', and not actually 'called'. To make my question clear, I rather expected just

setTimeout('expand(\''+element+'\')',8);

Because if it is stated in the variable, it seems to me that this method or function is just saved in the loopTimer, and be never used... but the code seems to work even if the loopTimer has not yet been 'called'..

Upvotes: 0

Views: 44

Answers (1)

Wyzard
Wyzard

Reputation: 34563

The setTimeout function returns a timeout ID that can be used to cancel the timeout later. This code is calling setTimeout and saving its result (the ID of the new timeout) in a variable so it can be passed to clearTimeout later.

To be clear: you're not saving the setTimeout function in the variable; you're saving the result of calling it. Just like target holds a DOM element returned by calling the document.getElementById function, not the function itself.

Upvotes: 2

Related Questions