JAVASCRIPT

JavaScript arrays: copying, transferring and merging

This series of articles mainly concentrates on working with JavaScript arrays. This is the third article in the series. It mainly concentrates on working with multiple arrays effectively. You can reuse these scripts to inject into server side controls easily (especially in .NET and Java).

Author Info:

By: Jagadish Chaterjee

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March 14, 2006

TABLE OF CONTENTS:

In this section I focus on transferring elements from one array to another. What is the difference between copying and transferring? The process of copying is “duplicating,” whereas the process of transferring is “moving.” “Moving” of elements means copying to another array and deleting from the original!

Now, let us try to develop a simple script (JavaScript) which transfers some of the elements present in the first array into the second. Have a look at the following code:

<html>

<head>

<!--

functionShow()

{

var SimpleString = "abc;def;ghi;jkl;mno;qrs";

var myArray = SimpleString.split(";");

var subArray = myArray.splice(0,3);

document.write("first array<br>---------<br>");

for (var i = 0; i < myArray.length; i++)

{

document.write(myArray[i] + "<BR>");

}

document.write("<br>second array<br>---------<br>");

for (var i = 0; i < subArray.length; i++)

{

document.write(subArray[i] + "<BR>");

}

functionButton1_onclick() {

Show();

}

//-->

</script>

</head>

<body>

</form>

</body>

</html>

When the above code is executed, the following output is generated.

first array
---------
jkl
mno
qrs

second array
---------
abc
def
ghi

Now you can observe the difference between the two outputs (compare the above output with the one in the first section). The elements from the first array have been removed and copied into the second array (which is what we call this “transferring” elements).

The only change I made in the above code is the following line:

var subArray = myArray.splice(0,3);

In the previous section, I used “slice” and now I am using “splice”. The “slice” makes you to copy the elements (without deleting from the source) whereas the “splice” makes you to transfer the elements (while deleting from the source).

Next: How to merge two arrays into a single array using JavaScript >>