jQuery, how do I find the max width of an object array?

Question

So, this is what I thought would work:

Math.max($j.map($j.makeArray($j(".rl_shell")), function(val, i){
    $j(val).width();
}));

breakdown:

$j.isArray($j.makeArray($j(".rl_shell")))

returns true

and when I do just

$j.map($j.makeArray($j(".rl_shell")), function(val, i){
        $j(val).width();
    })

I get an empty array ([]) as a result.

$j(".rl_shell")

returns [div, div]

so, I'm guessing, that I'm using map wrong, but I used the syntax here: http://api.jquery.com/jQuery.map/ so I'm not exactly sure what the deal is.

EDIT:

as per a couple of the answer's suggestions, I've come up with this:

$j.map($j.makeArray($j(".rl_shell")), function(val, i){
    return $j(val).width();
});

which returns [0,950]

but when I add Math.max around it, I get NaN =/

Felix Kling · Accepted Answer · 2012-01-23 15:24:28Z

4

Are you wanting to get the widest of all selected elements?

Math.max.apply(Math, $('selector').map(function(){ 
    return $(this).width(); 
}).get());

edited Jan 23, 2012 at 15:24

Felix Kling

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answered Jan 23, 2012 at 15:17

Will Stern

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3 Comments

NullVoxPopuli Over a year ago

I've come across an issue, I've updated my question to reflect the new problem.

NullVoxPopuli Over a year ago

why add the .get() at the end?

dfsq Over a year ago

.get converts jQuery object collection into native array. You have to provide an array to the .apply. So Math.max([0,950]) returns NaN while Math.max.apply(Math, [0, 950]) is equivalent to Math.max(0, 950) and returns 950.

dfsq · Accepted Answer · 2012-01-23 15:15:11Z

2

You just forget return from map callback:

Math.max($j.map($j.makeArray($j(".rl_shell")), function(val, i){
    return $j(val).width();
}));

answered Jan 23, 2012 at 15:15

dfsq

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2 Comments

NullVoxPopuli Over a year ago

bah, too used to ruby not requiring return o.o

NullVoxPopuli Over a year ago

I've come across an issue, I've updated my question to reflect the new problem.

xdazz · Accepted Answer · 2012-01-23 15:29:02Z

2

Besides you missed the return of the map callback,

You should use Math.max.apply(window, arr) to get the max value of an array.

Pass an array directly to Math.max will return NaN.

The code will be like below:

Math.max.apply(window, $.map($('.rl_shell'), function() {return $(this).width();}));

answered Jan 23, 2012 at 15:29

xdazz

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1 Comment

NullVoxPopuli Over a year ago

oh hey, that's exactly what I just ran into. =D

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