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Replacing elements at different positions of an array |
| Splice() is a powerful method in JavaScript array handling and it almost gives all type of element handling inside an array. We can add new element, we can remove some element, we can create new array by using (or taking) elements from an array. This is a method by which we can replace elements of an array with a new set of elements. Here is the general syntax of splice method when applied to our scripts array object ( this is the example of array we are using in all our previous array tutorials).
var t1=scripts.splice(starting_number,lenght,"list1");
Here scripts is our array object, starting_number is the array element number from where the starting element is to be taken up, length is the number of elements to be removed starting from the starting_number, list1 is the name of the element to be replaced. The replaced list can be more than the number of items to be removed. They will be added to the array. All the elements removed from scripts array will be placed in a new array t1.
Now let us try to understand how splice method works in different conditions. We will take our scripts array example, here is our array.
Replacing elements of an array using splice method
var scripts = new Array();
scripts[0] = "PHP";
scripts[1] = "ASP";
scripts[2] = "JavaScript";
scripts[3] = "HTML";
document.write(scripts.join(" <br> "));
document.write("<br>--Now after applying splice()--<br>");
var t1=scripts.splice(2,2,"VBScript","Perl");
document.write(scripts.join(" <br> "));
By using the above code you can see the last two elements of the scripts array is replaced with two new elements. The last two elements JavaScript and HTML are replaced by VBScript and Perl. This is how we can replace elements from any position by new elements. new array t1 will be holding the replaced array from the main array scripts.
Adding new elements without removing
Yes this also can be done, just make the number of elements to be removed to 0. The position where the new element to be added can be specified by starting_number. Here is the code to add two new elements after the second element.
var scripts = new Array();
scripts[0] = "PHP";
scripts[1] = "ASP";
scripts[2] = "JavaScript";
scripts[3] = "HTML";
document.write(scripts.join(" <br> "));
document.write("<br>--Now after applying splice()--<br>");
var t1=scripts.splice(2,0,"VBScript","Perl");
document.write(scripts.join(" <br> "));
Adding new element at the end of the array
We can do this by replacing starting_number with length of the array. In the above example replace the line with splice function with this one.
var t1=scripts.splice(scripts.length,0,"VBScript","Perl");
Adding new element at the beginning of the array
Same way we can add elements at the staring of the array by making the starting_number to 0
var t1=scripts.splice(0,0,"VBScript","Perl");
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