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JavaScript Array Operations

Author : Exforsys Inc. Published on: 29th Jul 2007

JavaScript Array Operations

In this JavaScript tutorial, you will learn about different operations with array in JavaScript, how to use the for...in statement, Combining Operations between arrays and within elements of an array, joining two or more arrays and joining elements of an arrays along with syntax and example scripts.

for…in statement:

The for…in statement is used for looping through the elements of the array.

The general structure of the for..in statement in JavaScript is as follows:

for (variablename in arrayname)
{
............
............ //Block of Code to be executed
}

<html>
   <body>
      <script type="text/javascript">
          var A
          var Exforsys=new Array()
          Exforsys[0] = "Training"
          Exforsys[1] = "Example"
          Exforsys[2] = "Company"

          for (A in Exforsys)
          {
          document.write(Exforsys[A] + "<br />")
          }
      </script>
   </body>
</html>

The output of the above example is

Training
Example
Company

In the above example, the variable name defined inside the for..in statement is A, which is used as an index for moving through the array Exforsys.

Combining Operations between arrays and within elements of an array:

It is possible to perform various operations between arrays and within elements of an array. One of these is the combining operation, which uses two aspects:

* Joining Two or more arrays
* Joining elements of a array

Joining two or more arrays:

The operation of Joining Two arrays can be performed using the predefined function concat( ).

The general format of concat( ) is:

arrayname1.concat(arrayname2,arrayname3,…….arraynamen)

<html>
   <body>
      <script type="text/javascript">
        var exforsys=new Array(4)
         exforsys[0]="Example1"
         exforsys[1]= "Example2"
         exforsys[2]= "Example3"
         exforsys[3]="Example4"

         var company=new Array(4)
         company[0]="Training1"
         company[1]="Training2"
         company[2]="Training3"
         company[3]="Training4"

         document.write(exforsys.concat(company))
      </script>
   </body>
</html>

The output of the above script is

Example1,Example2,Example3,Example4,Training1,Training2,Training3,Training4

In the above example we have concatenated elements of two arrays.

Joining elements of an array:

This is performed by using the join( ) method in JavaScript. The join method returns a string containing the elements of the array.

The general format of join( ) method is as follows:

arrayname.join(paramter)

In the above example, the parameter given is dot( . ), then each element of the joined array would be separated with a dot.

for example:

<html>
   <body>
      <script type="text/javascript">
                var exforsys=new Array(4)
        exforsys[0]="Example1"
        exforsys[1]= "Example2"
        exforsys[2]= "Example3"
        exforsys[3]="Example4"

        document.write(exforsys.join("."))
      </script>
   </body>
</html>