A multidimensional array is an array that contains another array. For example,

// multidimensional array
const data = [[1, 2, 3], [1, 3, 4], [4, 5, 6]];

Create a Multidimensional Array

Here is how you can create multidimensional arrays in JavaScript.

Example 1

let studentsData = [['Jack', 24], ['Sara', 23], ['Peter', 24]];

Example 2

let student1 = ['Jack', 24];
let student2 = ['Sara', 23];
let student3 = ['Peter', 24];

// multidimensional array
let studentsData = [student1, student2, student3];

Here, both example 1 and example 2 creates a multidimensional array with the same data.

Access Elements of an Array

You can access the elements of a multidimensional array using indices (0, 1, 2 …). For example,

let x = [
['Jack', 24],
['Sara', 23], 
['Peter', 24]
];

// access the first item 
console.log(x[0]); // ["Jack", 24]

// access the first item of the first inner array
console.log(x[0][0]); // Jack

// access the second item of the third inner array
console.log(x[2][1]); // 24

You can think of a multidimensional array (in this case, x), as a table with 3 rows and 2 columns.

Add an Element to a Multidimensional Array

You can use the Array’s push() method or an indexing notation to add elements to a multidimensional array.

Adding Element to the Outer Array

let studentsData = [['Jack', 24], ['Sara', 23],];
studentsData.push(['Peter', 24]);

console.log(studentsData); //[["Jack", 24], ["Sara", 23], ["Peter", 24]

Adding Element to the Inner Array

// using index notation
let studentsData = [['Jack', 24], ['Sara', 23],];
studentsData[1][2] = 'hello';

console.log(studentsData); // [["Jack", 24], ["Sara", 23, "hello"]]

// using push()
let studentsData = [['Jack', 24], ['Sara', 23],];
studentsData[1].push('hello');

console.log(studentsData); // [["Jack", 24], ["Sara", 23, "hello"]]

You can also use the Array’s splice() method to add an element at a specified index. For example,

let studentsData = [['Jack', 24], ['Sara', 23],];

// adding element at 1 index
studentsData.splice(1, 0, ['Peter', 24]);

console.log(studentsData); // [["Jack", 24], ["Peter", 24], ["Sara", 23]]

Remove an Element from a Multidimensional Array

You can use the Array’s pop() method to remove the element from a multidimensional array. For example,

Remove Element from Outer Array

// remove the array element from outer array
let studentsData = [['Jack', 24], ['Sara', 23],];
studentsData.pop();

console.log(studentsData); // [["Jack", 24]]

Remove Element from Inner Array

// remove the element from the inner array
let studentsData = [['Jack', 24], ['Sara', 23]];
studentsData[1].pop();

console.log(studentsData); // [["Jack", 24], ["Sara"]]

You can also use the splice() method to remove an element at a specified index. For example,

let studentsData = [['Jack', 24], ['Sara', 23],];

// removing 1 index array item
studentsData.splice(1,1);
console.log(studentsData); // [["Jack", 24]]

Iterating over Multidimensional Array

You can iterate over a multidimensional array using the Array’s forEach() method to iterate over the multidimensional array. For example,

let studentsData = [['Jack', 24], ['Sara', 23],];

// iterating over the studentsData
studentsData.forEach((student) => {
    student.forEach((data) => {
        console.log(data);
    });
});

Output

Jack
24
Sara
23

The first forEach() method is used to iterate over the outer array elements and the second forEach() is used to iterate over the inner array elements.

You can also use the for...of loop to iterate over the multidimensional array. For example,

let studentsData = [['Jack', 24], ['Sara', 23],];

for (let i of studentsData) {
  for (let j of i) {
    console.log(j);
  }
}

You can also use the for loop to iterate over a multidimensional array. For example,

let studentsData = [['Jack', 24], ['Sara', 23],];

// looping outer array elements
for(let i = 0; i < studentsData.length; i++){

    // get the length of the inner array elements
    let innerArrayLength = studentsData[i].length;
    
    // looping inner array elements
    for(let j = 0; j < innerArrayLength; j++) {
        console.log(studentsData[i][j]);
    }
}