Comparing numbers in javascript

Question

So here's my code:

var score1 = $(this).attr('data-score1');
var score2 = $(this).attr('data-score2');

if (score1 < score2) {
  // do some
}
if (score2 > score1) {
  // do something else
}

Now, this works fine as long as both variables are either both < or both > 100, yet whenever either of those variable is larger than 100 while the other is not the wrong if statement gets triggered. What the hell could be going on here? Thanks for any advice!

Dont know this language, but it probably compares them as strings — The Unfun Cat
– The Unfun Cat, Commented Oct 29, 2012 at 18:02
"90" is greater than "100" because "9" has a higher ascii value than "1". — Diodeus - James MacFarlane
– Diodeus - James MacFarlane, Commented Oct 29, 2012 at 18:03
Just so you know, jQuery isn't a language. You're programming in JavaScript. — Lusitanian
– Lusitanian, Commented Oct 29, 2012 at 18:04

Sushanth -- · Accepted Answer · 2012-10-29 18:10:46Z

7

Use parseInt()

The attributes will throw up strings.. So when you try to compare them... You are actually comparing

"100" > "90" and not 100 > 90 .. Using parseInt() with a radix should solve your problem..

var score1 = parseInt( $(this).attr('data-score1') , 10);
var score2 = parseInt( $(this).attr('data-score2') , 10);

if (score1 < score2) {
  // do some
}
else if (score2 > score1) {
  // do something else
}

As @naveen suggested you could do this as well

var score1 = +$(this).attr('data-score1');
var score2 = +$(this).attr('data-score2');

edited Oct 29, 2012 at 18:10

answered Oct 29, 2012 at 18:03

Sushanth --

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8 Comments

codeandcloud Over a year ago

dude, +$(this).attr('data-score1') will do

sachleen Over a year ago

@webarto that would make it score1 >= score2

Denys Séguret Over a year ago

@webarto : there could be a tie

kapa Over a year ago

@naveen parseInt() is much more readable. If you go for shortness (for some reason), you can use + of course.

kapa Over a year ago

@naveen You might or might not know that in Javascript unary + converts to number. If you see parseInt(), you already know what it does. If not, you have a function name to search on. I mean, yes, it is very clever that you know this trick, but do you really want to use it in code that other people will read?

|

sachleen · Accepted Answer · 2012-10-29 18:03:37Z

3

You're comparing the values as strings. The string "90" begins with 9, which has an ascii code that is greater than that of 1.

You can convert it to a number by using parseInt

parseInt(score1, 10)

answered Oct 29, 2012 at 18:03

sachleen

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