Jquery check for integer?

Question

I have this code:

    jQuery(function( $ ){

    // If no speed is set (when loading the page) set default speed

    if (!$moveSpeed) {
        var $moveSpeed = 4000;
    }

    // Move the damn autocue

 $('a.goDown').click(function(){
        alert($moveSpeed);
  $.scrollTo('#footer', $moveSpeed);
  return false;
 });

    $('a.goUp').click(function(){
        alert($moveSpeed);
  $.scrollTo('#header', $moveSpeed);
  return false;
 });


    // Speed settings for autocue

    $('a.changeSpeed').click(function(){
  $moveSpeed = $(this).attr('speed');
  return false;
 });
});

</script>

and if the changeSpeed is clicked, the alert box shows it is changed to the given number but it aint an integer, is there a way to convert a variable in to an integer?

thx :)

If you're going to put custom attributes on elements, strongly recommend using a data- prefix on them (e.g., data-speed). Custom attributes are invalid in HTML4 and earlier; in HTML5, they're valid if they start with data-. Browsers generally allow invalid attributes and so they work, but they make a document fail validation. More in this article — T.J. Crowder
– T.J. Crowder, Commented Dec 21, 2010 at 11:20

Jamiec · Accepted Answer · 2010-12-21 10:59:55Z

10

$('a.changeSpeed').click(function(){
  $moveSpeed = parseInt($(this).attr('speed'),10);
  return false;
 });

Javascript parseInt Function

answered Dec 21, 2010 at 10:59

Jamiec

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3 Comments

lonesomeday Over a year ago

+1 Nice use of parseInt, but it would be even nicer if you used this.speed rather than the unnecessary jQuery call!

Jamiec Over a year ago

@lonesomeday - what makes you think the current this has a property speed? I assumed it was an html attribute in which case the jQuery call is legit.

T.J. Crowder Over a year ago

@lonesomeday: Not all attributes are reflected as properties. I certainly wouldn't count on a non-standard and invalid one being reflected.

T.J. Crowder · Accepted Answer · 2010-12-21 11:16:09Z

I don't think it's the actual problem you're having, so I'm making this answer a CW, but FYI:

jQuery(function( $ ){

    // If no speed is set (when loading the page) set default speed

    if (!$moveSpeed) {
        var $moveSpeed = 4000;
    }

That if statement is completely non-functional, the body of it is always run. The !$moveSpeed condition will always be true. This is because var declares a variable within the current function, regardless of where the var statement actually is or whether it's inside a condition or loop. More details in this article, but basically the interpreter sees that code like this:

jQuery(function( $ ){
    var $moveSpeed;

    // If no speed is set (when loading the page) set default speed

    if (!$moveSpeed) {
        $moveSpeed = 4000;
    }

...and since the value of a variable that isn't initialized yet is undefined, and !undefined is true, you'll always set $moveSpeed to 4000.

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