Details
You can use various methods to modify arrays. To use an array method, write the name of the variable containing the array, add a period, the method name, and a pair of parentheses. The general format looks like this:
arrayName.method();Some methods take one or more values, like this:
arrayName.method(value);
arrayName.method(value, value);
arrayName.method(value, value, value);Add item(s) to end
To add item(s) to the end of an array, use the push() method. Place one or more values inside the parentheses, like this:
let letters = ['a', 'b', 'c'];
letters.push('d');
// letters = ['a', 'b', 'c', 'd']let letters = ['a', 'b', 'c'];
letters.push('d', 'e', 'f');
// letters = ['a', 'b', 'c', 'd', 'e', 'f']Remove last item
To remove the last item from an array, use the pop() method.
let letters = ['a', 'b', 'c'];
letters.pop();
// letters = ['a', 'b']Add item(s) to beginning
To add item(s) to the beginning of an array, use the unshift() method. Place one or more values inside the parentheses, like this:
let letters = ['a', 'b', 'c'];
letters.unshift('d');
// letters = ['d', 'a', 'b', 'c']let letters = ['a', 'b', 'c'];
letters.unshift('d', 'e', 'f');
// letters = ['d', 'e', 'f', 'a', 'b', 'c']Remove first item
To remove the first item from an array, use the shift() method.
let letters = ['a', 'b', 'c'];
letters.shift();
// letters = ['b', 'c']Insert item at specific index
To insert an item at a specific index, use the splice() method. In this case, the splice() takes 3 arguments. The first argument is the index where you want to insert an item. The second argument must be 0. The last argument is the value you want to insert.
let letters = ['a', 'b', 'c'];
letters.splice(1, 0, 'd');
// letters = ['a', 'd', 'b', 'c']Remove item(s) at specific index
To remove an item at a specific index, use the splice() method. In this case, the splice() takes 2 arguments. The first argument is the index where you want to insert an item. The second argument is the number of items you want to remove.
let letters = ['a', 'b', 'c'];
letters.(1, 1);
// letters = ['a', 'c']Replace item(s)
To replace an item at a specific index, use the splice() method. In this case, the splice() takes 3 arguments. The first argument is the index where you want to insert an item. The second argument is the number of items you want to replace. The last argument is the value (or values) you want to insert.
let letters = ['a', 'b', 'c'];
letters.splice(1, 1, 'd');
// letters = ['a', 'd', 'c']Demo
Exercises
Create the letters array like in the code snippets above in your browser console in a new tab. Then try the various array methods on it. You can refresh the page if you’d like to start from scratch for each method.