Use Array unshift method to insert an element at 0 indexes into the JavaScript array. The unshift. It’s like push, except it adds elements to the beginning of the array instead of the end.
array.unshift(item1, item2, ..., itemX)unshift/push– add an element to the beginning/end of an arrayshift/pop– remove and return the first/last element of an array
A simple diagram
unshift -> array <- push
shift <- array -> popSource: stackoverflow.com
JavaScript array insert at 0
Simple example code adds new elements to the beginning of an array.
<!DOCTYPE html>
<html>
<body>
<script>
const fruits = ["B", "O", "A", "M"];
fruits.unshift("X","Y");
console.log(fruits)
</script>
</body>
</html> Output:
More example
var a = [23, 45, 12, 67];
a.unshift(34);
console.log(a);With ES6, use the spread operator ...:
var arr = [23, 45, 12, 67];
arr = [34, ...arr]; // RESULT : [34,23, 45, 12, 67]
console.log(arr)Another way to do that is through concat:
var arr = [1, 2, 3, 4, 5, 6, 7];
console.log([0].concat(arr));The difference between concat and unshift is that concat returns a new array. The performance between them could be found here.
Do comment if you have any doubts or suggestions on this JS array topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version