JavaScript arrays: copying, transferring and merging - How to merge two arrays into a single array using JavaScript: discussion

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Within the code in the previous section, I mainly created a simple button (which is identified as “ButtonMerge”).  The button is defined with an “onclick” event which calls a JavaScript function, “ButtonMerge_onclick.”  The same function simply calls another JavaScript function named “Show.”

The function “Show” is defined as follows:

functionShow()

{

      var myArray1 = new Array();

      myArray1[0] = "Jag";

      myArray1[1] = "Chat";

      myArray1[2] = "Win";

      myArray1[3] = "Dhan";

     

      var myArray2 = new Array();

      myArray2[0] = "aaa";

      myArray2[1] = "bbb";

      myArray2[2] = "ccc";

      myArray2[3] = "ddd";

     

      var myArray3 = myArray1.concat(myArray2);

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

      for (var i = 0; i < myArray3.length; i++)

      {

            document.write(myArray3[i] + "<BR>");

      }

}

Let us go through the above code part by part.  Let us consider the first part as follows:

      var myArray1 = new Array();

      myArray1[0] = "Jag";

      myArray1[1] = "Chat";

      myArray1[2] = "Win";

      myArray1[3] = "Dhan";

The above part creates a new array named “myArray1” and adds four elements to the same array. These elements are “Jag,””Chat,””Win” and ”Dhan.”  The following is very similar to the above fragment except that we named the second array “myArray2.”

      var myArray2 = new Array();

      myArray2[0] = "aaa";

      myArray2[1] = "bbb";

      myArray2[2] = "ccc";

      myArray2[3] = "ddd";

Further proceeding we have the following:

      var myArray3 = myArray1.concat(myArray2);

The above statement creates a new array with all the elements from both “myArray1” and “myArray2” and finally assigns the new array (a merged array) to the variable “myArray3.”  We display the merged array using the following (as explained in the first article):

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

      for (var i = 0; i < myArray3.length; i++)

      {

            document.write(myArray3[i] + "<BR>");

      }

While the process of merging is going on, neither of the two arrays (“myArray1” and “myArray2”) is modified.  If you want to view both arrays, you can add the following code at the end of the function:

      document.write("First array after merging<br>----------------<br>");

      for (var i = 0; i < myArray1.length; i++)

      {

            document.write(myArray1[i] + "<BR>");

      }

      document.write("Second array after merging <br>----------------<br>");

      for (var i = 0; i < myArray2.length; i++)

      {

            document.write(myArray2[i] + "<BR>");

      }

That should make you understand that “myArray1” and “myArray2” are constant (not modified) and only “myArray3” gets created (or merged).

Any comments, suggestions, ideas, improvements, bugs, errors, feedback etc. are highly appreciated at jag_chat@yahoo.com.

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