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JavaScript array position

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In this section of JavaScript array tutorial we have to find the position of the array items.

JavaScript array position

     

In this section of JavaScript array tutorial we have to find the position of the array items. There is not any built in method in the JavaScript by which we can find the position of the array item therefore we have created a method getPosition() which takes two arguments: first is the array object and second is the item of which we have to find the position.

In this example of getting position we have traversed whole array for finding array element's position and where the specified item matched with the array elements it returns the index i.e the position of array item.

function getPosition(arrayName,arrayItem)
{
  for(var i=0;i<arrayName.length;i++){ 
   if(arrayName[i]==arrayItem)
  return i;
  }
}

Above lines of code defines a function getPosition(arrayName, arrayItem) for getting the index or position of the specified array item. Here is the full HTML example code of javascript_array_position.html as follows:

 javascript_array_position.html

<html>
<head>
<title>
JavaScript array position example
</title>
<script type="text/javascript">
var arr = new Array(5);
arr[0]="Rose";
arr[1]="India";
arr[2]="Technologies";
arr[3]="Pvt";
arr[4]="Ltd";
function getPosition(arrayName,arrayItem)
{
  for(var i=0;i<arrayName.length;i++){ 
   if(arrayName[i]==arrayItem)
  return i;
  }
}
document.write("<h2>Index position of item \"India\" is ="+getPosition(arr,"Rose")+"</h2>");
document.write("<h2>Index position of item \"Pvt\" is ="+getPosition(arr,"Pvt")+"</h2>");
</script>
</head>
<body bgcolor="#ddcdff">
  <h2>
   JavaScript array find position
   </h2>
</body>
</html>

Output of the example is as follows:

Download Sample Source Code

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Posted on: November 10, 2008

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Comments:1
Brokenclock
December 6, 2011
Can do better

Well, your code does not work if you have an indexed array where some index are missing... For exemple, with the array {4: "Cat",5: "Dog",7: "Lion"} your fonction will never return the actual position of the seached item but only its index. You should better use the for...in statement like this : function getPosition(arrayName,arrayItem){ var i=0; for (item in arrayName){ if (item==arrayItem) return i; i++; } } Well, this function return 0 for the first position, as usual.
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