check if element is in array using jquery

**ggalan** · 02-12-2012, 01:45 AM

i have left/right buttons, the right button pushes elements into an array.
if the user pushes the left button then pushes the right button, i want to check the right number against the array.
heres my code so far, any help would be greatly appreciated

Code:

<!DOCTYPE HTML>
<html lang="en-US">
<head>
<style type="text/css">
div{float:left; margin-right:50px;}
</style>
<script src="http://code.jquery.com/jquery.min.js"></script>
<script type="text/javascript">
var num = 0;
var arr = [];
$(function(){
	$('#btn1').click(function() {
		num--;
		$('#rec').html(num);
		return false;
	});
	
	$('#btn2').click(function() {
		num++;
		arr.push(num);
		$('#rec').html(num);
		
		if(  jQuery.inArray(num, arr)  ){// doesnt work
		// do nothing
		}else{
			$('#arrayRec').html(arr.join(','));
		}
		return false;
	});
});
</script>
</head>
<body>
<div id="btn1"><a href="">left</a></div>
<div id="btn2"><a href="">right</a></div>
<div id="rec">0</div>
<div id="arrayRec">null</div>
</body>
</html>

**jscheuer1** · 02-12-2012, 03:34 AM

jQuery.inArray(item, array) returns the index of the item in the array or -1 if the item is not present. So your test:

Code:

if(  jQuery.inArray(num, arr)  )

should be:

Code:

if(  jQuery.inArray(num, arr) > -1 )

Which will return true if the number num is in the array arr. And since it always is, nothing will ever be sent to the arrayRec div.

A better illustration of the utility of inArray might be:

Code:

<script type="text/javascript">
var num = 0;
var arr = [];
$(function(){
	$('#btn1').click(function() {
		num--;
		$('#rec').html(num);
		return false;
	});
	
	$('#btn2').click(function() {
		num++;
		$('#rec').html(num);

		if( jQuery.inArray(num, arr) < 0 ){ // if the number isn't already in the array
			arr.push(num); // put it in the array and
			$('#arrayRec').html(arr.join(',')); // update the report of the array's contents
		}
		return false;
	});
});
</script>

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