CODEWITHSUNDEEP
javascriptjquerymath
SorenRomer
SorenRomer

Reputation: 217

Formula not calculating correctly in JavaScript

I'm experiencing an issue with a formula in JavaScript.

var animMoveX = $(this).attr('data-start') + (animPercentage / 100) * ($(this).attr('data-finish') - $(this).attr('data-start'));

To my eyes it's a fairly simple piece of math, but the console outputs 120-[variable no relative to animPercentage, eg. 126.49681528662421].

I've double-checked all variables, and they are correct, and if I replace one of the $(this).attr('data-start') variable in one of the positions with a fixed number, then the calculation is run just fine. Can someone shed some light on why this is, and how I could potentially work around it?

Upvotes: 1

Views: 75

Answers (1)

iCollect.it Ltd
iCollect.it Ltd

Reputation: 93551

From my comment: Precedence means it will calculate a number on the right and add it to the string from data-start (i.e. using string concatenation). That needs to be converted to a number too. @Pointy's suggestion will do that as data converts strings to appropriate data types (when it can).

So basically change all the attr() calls to data() calls and "numbers" (stored in attributes) will become numbers:

var animMoveX = $(this).data('start') + (animPercentage / 100) * ($(this).data('finish') - $(this).data('start'));

As an added bonus, using data instead of attr is shorter code too :)

Upvotes: 2

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