Jquery/Javascript : Negative of a Variable

Question

What's the best way to check for the negative of a variable?

Here are my variables:

var frameWidth = 400;
var imageWidth = parseInt($('#' + divId).find('#inner-image').css('width'), 10);
var imageMargin = parseInt($('#' + divId).find('#inner-image').css('margin-left'), 10);
var numberOfFrames = imageWidth/frameWidth;

I want to perform a check kind of like this:

if (imageMargin == -numberOfFrames*frameWidth-400 )

But I don't know how.

In other words, if numberOfFrames*frameWidth-400 equals 800, I need it to return -800.

Thanks again for any direction you can provide.

sth · Accepted Answer · 2011-02-11 16:42:55Z

9

There should be no problems if you put parenthesis around the value you want to negate:

if (imageMargin == -(numberOfFrames*frameWidth-400) )
   ...

answered Feb 11, 2011 at 16:42

sth

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1 Comment

MrWhite Over a year ago

@Rrryyyaaannn If the result of (numberOfFrames*frameWidth-400) is itself negative then the expression above will check for the positive... is that OK? @Matt's function getNegativeOf() will always return the negative.

Matt · Accepted Answer · 2011-02-11 16:35:56Z

4

If you always want a negative value, and you don't know if it'll be positive or negative:

function getNegativeOf(val) {
    return Math.abs(val) * -1;
};

Then use as:

var guaranteedNegativeImageWidth = getNegativeOf(parseInt($('#' + divId).find('#inner-image').css('width'), 10));

answered Feb 11, 2011 at 16:35

Matt

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Comments

Ben Jakuben · Accepted Answer · 2011-02-11 16:33:38Z

0

How about subtracting it from zero?

if (imageMargin == (0-(numberOfFrames*frameWidth-400)) )

answered Feb 11, 2011 at 16:33

Ben Jakuben

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