How functions get evaluated in Jquery.?

Question

My HTML,

<div id="fullcontainer">
    <div id="a">a</div>
    <div id="b">b</div>
    <div id="c">c</div>
</div>

JS,

   var cache = $('#fullcontainer').children();
   var index = cache.length - 2;
   cache.filter(':lt('+ index +')').remove();

The code that i had given above is working fine as expected, since i have cached the length in a separate variable, But the following code without caching is not working,

   var cache = $('#fullcontainer').children();
   cache.filter(':lt('+ cache.length - 2 +')').remove();

As far as i have learned the expressions at the last level should be evaluated first, But i dont know what is happening with the above piece of codes, Please advice and provide some explanations.

DEMO of the working one, Demo of the non - working one

Rohan Kumar · Accepted Answer · 2014-03-05 05:11:21Z

2

Its will work if you enclose cache.length - 2 in brackets like,

cache.filter(':lt('+ (cache.length - 2) +')').remove();

Working Demo

answered Mar 5, 2014 at 5:11

Rohan Kumar

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3 Comments

Rajaprabhu Aravindasamy Over a year ago

But i had given a space outside them.? So spaces are not considered in JS.. Am i right.?

zzzzBov Over a year ago

@RajaprabhuAravindasamy, order of operations says that ':lt(' + cache.length happens before the - 2. Spaces don't change the order, but parenthesis do.

Rohan Kumar Over a year ago

Agreed with @zzzzBov. Spaces only provide you better readability. Expressions must be enclosed in brackets not in js but in any language.

Arun P Johny · Accepted Answer · 2014-03-05 05:11:25Z

2

Your code cache.filter(':lt('+ cache.length - 2 +')').remove(); get evaluated to

cache.filter('NaN)').remove();

it should be

cache.filter(':lt('+ (cache.length - 2) +')').remove();

answered Mar 5, 2014 at 5:11

Arun P Johny

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Comments

Felix · Accepted Answer · 2014-03-05 05:11:29Z

2

You need to wrap your value in brackets ( ) to make it evaluated as number:

cache.filter(':lt('+ (cache.length - 2) +')').remove();

Updated Fiddle

answered Mar 5, 2014 at 5:11

Felix

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