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Append / Prepend items to an Array

There are four methods used to append/prepend items to an Array. They are:

  • Array push method
  • Array pop method
  • Array unshift method
  • Array shift method

Push​

Use .push() to add one or more items from the end of an array.

Syntax​

push(element0)
push(element0, element1)
push(element0, element1, ..., elementN)

Example​

var array = [3, 4, 5, 6];
array.push(1, 2);
console.log(array);
// expected output: [3, 4, 5, 6, 1, 2];

A new array is returned with new length.

Pop​

The .push() is used to remove the last element from the array and returns this element.

Syntax​

pop()

Example​

var array = [3, 2, 9, 15, 22, 1];
var poppedElement = array.pop();
console.log(poppedElement);
// expected output: 1
console.log(array);
// expected output: [2, 9, 15, 22]
var poppedElement = array.pop();
console.log(poppedElement);
// expected output: 22
console.log(array);
// expected output: [1, 2, 9, 15]

At a time, one element can be popped from the array.

Unshift​

The .unshift() method is used to insert one or more elements at the start/beginning of the array

Syntax​

unshift(element0)
unshift(element0, element1)
unshift(element0, element1, ..., elementN)

Example​

var array = [12, 5, 4, 23];
array.unshift(20, 55, [10, 21]);
console.log(array);

A new array is returned with new length.

Shift​

The .shift() method is used to remove the first element from the array.

Syntax​

shift()

Example​

var array = [12, 15, 25, 66, 1];
var shiftedElement = array.shift();
console.log(shiftedElement);
// expected output: 12
console.log(array);
// expected output: [15, 25, 66, 1];
var shiftedElement = array.shift();
console.log(shiftedElement);
// expected output: 15
console.log(array);
// expected output: [25, 66, 1];