How do you add, remove, and update elements in an array?
TL;DR
To add elements to an array, you can use methods like push, unshift, or splice. To remove elements, you can use pop, shift, or splice. To update elements, you can directly access the array index and assign a new value.
let arr = [1, 2, 3];// Add elementsarr.push(4); // [1, 2, 3, 4]arr.unshift(0); // [0, 1, 2, 3, 4]arr.splice(2, 0, 1.5); // [0, 1, 1.5, 2, 3, 4]// Remove elementsarr.pop(); // [0, 1, 1.5, 2, 3]arr.shift(); // [1, 1.5, 2, 3]arr.splice(1, 1); // [1, 2, 3]// Update elementsarr[1] = 5; // [1, 5, 3]
Adding elements to an array
Using push
The push method adds one or more elements to the end of an array and returns the new length of the array.
let arr = [1, 2, 3];arr.push(4); // arr is now [1, 2, 3, 4]
Using unshift
The unshift method adds one or more elements to the beginning of an array and returns the new length of the array.
let arr = [1, 2, 3];arr.unshift(0); // arr is now [0, 1, 2, 3]
Using splice
The splice method can add elements at any position in the array. The first parameter specifies the index at which to start changing the array, the second parameter specifies the number of elements to remove, and the rest are the elements to add.
let arr = [1, 2, 3];arr.splice(1, 0, 1.5); // arr is now [1, 1.5, 2, 3]
Removing elements from an array
Using pop
The pop method removes the last element from an array and returns that element.
let arr = [1, 2, 3];arr.pop(); // arr is now [1, 2]
Using shift
The shift method removes the first element from an array and returns that element.
let arr = [1, 2, 3];arr.shift(); // arr is now [2, 3]
Using splice
The splice method can also remove elements from any position in the array. The first parameter specifies the index at which to start changing the array, and the second parameter specifies the number of elements to remove.
let arr = [1, 2, 3];arr.splice(1, 1); // arr is now [1, 3]
Updating elements in an array
Direct assignment
You can update elements in an array by directly accessing the index and assigning a new value.
let arr = [1, 2, 3];arr[1] = 5; // arr is now [1, 5, 3]