AJAX

How can we delete array in javascript?

Please support our JavaScript / DHTML / AJAX advertiser: PostgreSQL or MySQL? Compare and contrast the two most popular open source databases

Thread Solved

•

Join Date: Aug 2006

Posts: 319

Reputation: Luckychap is on a distinguished road

Solved Threads: 42

Luckychap

Offline

Posting Whiz

How can we delete array in javascript?

Aug 19th, 2009

Hi all,

I want help from all you wonderful guys. I want to know how can we free memory occupied by an Array. That means all the elements associated with this array should be deleted.

let say:

 Help with Code Tags 
 javascript Syntax (Toggle Plain Text) 
var bigArray = ["313123", "123123", "sadasd",.........................];
var bigArray = ["313123", "123123", "sadasd",.........................];

So which will be the best and assured way :

1)

Help with Code Tags

javascript Syntax (Toggle Plain Text)

 delete bigArray;

OR
2)

Help with Code Tags

javascript Syntax (Toggle Plain Text)

 bigArray = [];

OR
3) any other ...

Thanks,

When you think you have done a lot, then be ready for YOUR downfall.

•

Join Date: Jan 2008

Posts: 2,052

Reputation: serkan sendur is a glorious beacon of light

Solved Threads: 118

serkan sendur serkan sendur is offline

Offline

Postaholic

Re: How can we delete array in javascript?

Aug 19th, 2009

wow i have created big javascript applications so far and yet i have never needed to delete something from memory. why do you need it?

Due to lack of freedom of speech, i no longer post on this website.

•

Join Date: Aug 2008

Posts: 954

Reputation: essential will become famous soon enough

Solved Threads: 131

essential

Offline

Posting Shark

Re: How can we delete array in javascript?

Aug 19th, 2009

Hi everyone,

Lucky,
here's a simple demo, showing how you can removed items inside your array using the pop(index) method.

 Help with Code Tags 
 javascript Syntax (Toggle Plain Text) 
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Script-Type" content="text/javascript">
<title>www.daniweb.com</title>
<script type="text/javascript">
<!--
 
window.onload = function() {
var bigArray = [];
 
   for ( var i = 0; i < 500; i++ ) { // creating 500 items into bigArray >>> 
      bigArray[ i ] = "Item" + i;
   } alert("bigArray has a total of " + ( bigArray.length ) + " items inside its collection");
   var aLen = ( bigArray.length - 1 ); 
   for ( var x = aLen; bigArray[ x ]; x-- ) { // Removing all 500 items from the bigArray.
      bigArray.pop( x ); 
   } alert( "\nAll items' from the ( bigArray ) has been removed.\nItem count: " + bigArray.length ); 
};
// --> 
</script>
</head>
<body>
<div></div>
</body>
</html>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Script-Type" content="text/javascript">
<title>www.daniweb.com</title>
<script type="text/javascript">
<!--

window.onload = function() {
var bigArray = [];

   for ( var i = 0; i < 500; i++ ) { // creating 500 items into bigArray >>> 
      bigArray[ i ] = "Item" + i;
   } alert("bigArray has a total of " + ( bigArray.length ) + " items inside its collection");
   var aLen = ( bigArray.length - 1 ); 
   for ( var x = aLen; bigArray[ x ]; x-- ) { // Removing all 500 items from the bigArray.
      bigArray.pop( x ); 
   } alert( "\nAll items' from the ( bigArray ) has been removed.\nItem count: " + bigArray.length ); 
};
// --> 
</script>
</head>
<body>
<div></div>
</body>
</html>

Last edited by essential; Aug 19th, 2009 at 3:26 am.

Dev.Opera — FOLLOW THE STANDARDS, BREAK THE RULES...

•

Join Date: Jan 2008

Posts: 2,052

Reputation: serkan sendur is a glorious beacon of light

Solved Threads: 118

serkan sendur serkan sendur is offline

Offline

Postaholic

Re: How can we delete array in javascript?

Aug 19th, 2009

i dont think he is looking for such a processor consuming way of deleting the memory. i think delete keyword works better for his needs. or basically setting the array to null.

Due to lack of freedom of speech, i no longer post on this website.

•

Join Date: Aug 2008

Posts: 954

Reputation: essential will become famous soon enough

Solved Threads: 131

essential

Offline

Posting Shark

Re: How can we delete array in javascript?

Aug 19th, 2009

Obtaining serkan's adviced of way of freeing the memory and minimized the above application:

Help with Code Tags

(Toggle Plain Text)

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Script-Type" content="text/javascript">
<title>www.daniweb.com</title>
<script type="text/javascript">
<!--

window.onload = function() {
   var bigArray = [];  
   bigArray2 = [];
   for ( var i = 0; i < 500; i++ ) { // creating 500 items into bigArray >>> 
      bigArray[ i ] = "Item" + i;
      bigArray2[ i ] = "Item" + i;
   } 
/*
  You can use the delete operator to delete variables declared implicitly but not those declared with the var statement. 

Output Sample: */

delete bigArray; // ignore's the delete process.

alert( bigArray.length ); // outputs the same length

// either one of the following statement will work, if you have defined it using the var statement.

bigArray = null; // or:

// bigArray = []; // reset's all items...

delete bigArray2; // this one works and delete's the bigArray2 variable.

};
// --> 
</script>
</head>
<body>
<div></div>
</body>
</html>

Dev.Opera — FOLLOW THE STANDARDS, BREAK THE RULES...

•

Join Date: Jan 2008

Posts: 2,052

Reputation: serkan sendur is a glorious beacon of light

Solved Threads: 118

serkan sendur serkan sendur is offline

Offline

Postaholic

Re: How can we delete array in javascript?

Aug 19th, 2009

Thanks for taking me into consideration

Due to lack of freedom of speech, i no longer post on this website.

•

Join Date: Aug 2006

Posts: 319

Reputation: Luckychap is on a distinguished road

Solved Threads: 42

Luckychap

Offline

Posting Whiz

Re: How can we delete array in javascript?

Aug 19th, 2009

Thanks gentlemen,

So, using 'delete' OR '[]' will delete all the items (and memory) associated with the array.

Please confirm this.

When you think you have done a lot, then be ready for YOUR downfall.

•

Join Date: Aug 2008

Posts: 954

Reputation: essential will become famous soon enough

Solved Threads: 131

essential

Offline

Posting Shark

Re: How can we delete array in javascript?

Aug 19th, 2009

Hi lucky,

both ways will provide the same results, the only difference between the two procedure, is that when you use the delete operator, your variable will no longer be accessible within the function unless you redefined it.

Hope we've claimed your needs...

@serkan - welcome

, you had a better solution compared to my first post.

Dev.Opera — FOLLOW THE STANDARDS, BREAK THE RULES...

•

Join Date: Aug 2006

Posts: 319

Reputation: Luckychap is on a distinguished road

Solved Threads: 42

Luckychap

Offline

Posting Whiz

Re: How can we delete array in javascript?

Aug 19th, 2009

•

Originally Posted by serkan sendur

wow i have created big javascript applications so far and yet i have never needed to delete something from memory. why do you need it?

We usually encounter this problem when working with embedded devices (settop boxes etc.) where there is very less memory. We need to free memory where ever its possible.

When you think you have done a lot, then be ready for YOUR downfall.