JavaScript Array unshift()

The JavaScript Array unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.

The syntax of the unshift() method is:

arr.unshift(element1, element2, ..., elementN)

Here, arr is an array.


unshift() Parameters

The unshift() method takes in an arbitrary number of elements to add to the array.


Return value from unshift()

  • Returns the new (after adding arguments to the beginning of array) length of the array upon which the method was called.

Notes:

  • This method changes the original array and its length.
  • To add elements to the end of an array, use the JavaScript Array push() method.

Example: Using unshift() method

var languages = ["JavaScript", "Python", "Java", "Lua"];

var count = languages.unshift("C++");
console.log(languages); // [ 'C++', 'JavaScript', 'Python', 'Java', 'Lua' ]
console.log(count); // 5

var priceList = [12, 21, 35];

var count1 = priceList.unshift(44, 10, 1.6);
console.log(priceList); // [ 44, 10, 1.6, 12, 21, 35 ]
console.log(count1); // 6

Output

[ 'C++', 'JavaScript', 'Python', 'Java', 'Lua' ]
5
[ 44, 10, 1.6, 12, 21, 35 ]
6

Recommended Readings: