How to add array element at specific index in JavaScript?
To insert element into JavaScript array,
splice method
should be used. For inserting first parameter should be index
before which new element will be inserted. Indexes are
counted from zero. Second parameter should be 0 as we
do not remove element. The splice method must be called on array
itself and it will modify this array.
Example of inserting at beginning
Use index value of zero to insert at beginning.
var x = [111, 222, 333]; x.splice(0, 0, 666); // Array is now [666, 111, 222, 333]
Inserting at arbitrary index
Passing as parameter on integer value greater than zero, results in adding element before that index value.
var x = [111, 222, 333]; x.splice(2, 0, 666); // Array is now [111, 222, 666, 333]
Out of range index
If we set index parameter to be greater than maximum existing
array index or negative value, the new element will be appended
to end of array. However good practice is to avoid such
constructs, instead use
array.length or
better push method.
Adding element to end of array
The easiest way is to use push method.
var x = [111, 222, 333];
x.push(666);
// [111, 222, 333, 666]
