Multidimensional array in JavaScript

Last Updated : 23 Oct, 2019

Multidimensional arrays are not directly provided in JavaScript. If we want to use anything which acts as a multidimensional array then we need to create a multidimensional array by using another one-dimensional array. So multidimensional arrays in JavaScript is known as arrays inside another array. We need to put some arrays inside an array, then the total thing is working like a multidimensional array. The array, in which the other arrays are going to insert, that array is use as the multidimensional array in our code. To define a multidimensional array its exactly the same as defining a normal one-dimensional array.

One-Dimensional array:

var arr = []; // Empty 1D array
var arr1 = ["A", "B", "C", "D"] // 1D array contains some alphabets
var arr1 = [1, 2, 3, 4, 5] // 1D array contains some digits

Multidimensional-Dimensional array:

Method 1:

1st, need to define some 1D array
var arr1 = ["ABC", 24, 18000];
var arr2 = ["EFG", 30, 30000];
var arr3 = ["IJK", 28, 41000];
var arr4 = ["EFG", 31, 28000];
var arr5 = ["EFG", 29, 35000];
// "salary" defines like a 1D array but it already contains some 1D array
var salary = [arr1, arr2, arr3, arr4, arr5];

Here arr1, arr2, …arr5 are some 1D arrays which are inside salary array.

Method 2:

var salary = [
   ["ABC", 24, 18000],
   ["EFG", 30, 30000],
   ["IJK", 28, 41000],
   ["EFG", 31, 28000],
];

Here, salary array works like a multidimensional array. This notations are known as array literals.

Accessing the element of salary array:

To access the array element we need a simple index based notation

// This notation access the salary of "ABC" person which is 18000, 
// [0] selects 1st row, and [2] selects the 3rd element
// of that 1st row which is 18000
salary[0][2];

// Similarly, 
salary[3][2]; // Selects 28000

**This notation is used for both Method 1 and Method 2.

For many iteration, we need to use loop to access the elements,

// This loop is for outer array
for (var i = 0, l1 = salary.length; i < l1; i++) {

    // This loop is for inner-arrays
    for (var j = 0, l2 = salary[i].length; j < l2; j++) {

        // Accessing each elements of inner-array
        documents.write( salary[i][j] ); 
    }
}

Adding elements in Multidimensional Array: Adding elements in multi-dimensional arrays can be achieved in two ways in inner array or outer array. The inner array can be done in two different ways.

Adding elements to inner array:

We can use simple square bracket notation to add elements in multidimensional array.

salary[3][3] = "India";

// It adds "India" at the 4th index of 4th sub-array,
// If we print the entire 4th sub-array, document.write(salary[3]);
// the output will be :  ["EFG", 31, 28000, "India"]
// indexing starts from 0

We can use push() method to add elements in the array.

salary[3].push("India", "Mumbai");

// It add "India" at the 4th index and "Mumbai" at
// 5th index of 4th sub-array
// If we print the entire 4th sub-array,
// document.write(salary[3]);
// The output will be :  ["EFG", 31, 28000, "India", "Mumbai"]
// Indexing starts from 0

Adding elements to outer array: It is much similar to previous methods.

salary.push(["MNO", 29, 33300]);
// This row added after the last row in the "salary" array

Removing elements in Multidimensional Array: We can use pop() methods to remove elements from inner-arrays, and also use pop() method for removing a entire inner array.

// Remove last element from 4th sub-array
// That is 28000 indexing starts from 0
salary[3].pop(); 

// Removes last sub-array
// That is "["EFG", 31, 28000]"
salary.pop();

Example 1:

// Prints a simple multidimensional array in JavaScript
<script>
var arr1 = ["ABC", 24, 18000];
var arr2 = ["EFG", 30, 30000];
var arr3 = ["IJK", 28, 41000];
var arr4 = ["EFG", 31, 28000];
var arr5 = ["EFG", 29, 35000];
var salary = [arr1, arr2, arr3, arr4, arr5]; 
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
</script>

Output:

ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000
EFG, 29, 35000

Example 2:

// Prints a simple multidimensional array in
// JavaScript with different declaration
<script>
var salary = [
   ["ABC", 24, 18000],
   ["EFG", 30, 30000],
   ["IJK", 28, 41000],
   ["EFG", 31, 28000],
]; 
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
</script>                    

Output:

ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000
EFG, 29, 35000

Example 3:

// Prints a simple multidimensional array in JavaScript
// where we just print the salary of a specific person
<script>
var salary = [
   ["ABC", 24, 18000],
   ["EFG", 30, 30000],
   ["IJK", 28, 41000],
   ["EFG", 31, 28000],
]; 
document.write("salary of 2nd person : " + salary[1][2] + "<br>");
document.write("salary of 4th person : " + salary[3][2] + "<br>");
</script>                    

Output:

salary of 2nd person : 30000
salary of 4th person : 28000

Example 4:

// Prints a simple multidimensional array in
// JavaScript where we add elements in the array 
// using simple square bracket and push() method
<script>
var salary = [
   ["ABC", 24, 18000],
   ["EFG", 30, 30000],
   ["IJK", 28, 41000],
   ["EFG", 31, 28000],
]; 
  
// Prints first array
document.write("Original array :<br>");
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
  
// Adding "India" at the 4th index of 4th sub array
salary[3][3] = "India";
  
document.write("<br>after adding \"India\" at the 4th array :<br>");
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
  
document.write("<br>after adding \"USA\" and \"Canada\" "
     + "at the 3rd array using \"push()\" method :<br>");
salary[2].push("USA", "Canada");
  
// Adding "USA" and "Canada" in the 2nd sub-array
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
</script> 

Output:

Original array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000

after adding "India" at the 4th array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000, India

after adding "USA" and "Canada" at the 3rd array using "push()" method :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000, USA, Canada
EFG, 31, 28000, India

Example 5:

// Prints a simple multidimensional array in
// JavaScript where we add a new inner array 
<script>
var salary = [
   ["ABC", 24, 18000],
   ["EFG", 30, 30000],
   ["IJK", 28, 41000],
   ["EFG", 31, 28000],
]; 
  
// Prints first array
document.write("Original array :<br>");
  
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
  
document.write("<br>After adding a new inner array :<br>");
  
// Pushing a new sub-array
salary.push(["MNO", 29, 33300]);
  
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
</script> 

Output:

Original array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000

After adding a new inner array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000
MNO, 29, 33300

Example 6:

// Prints a simple multidimensional array in
// JavaScript where we remove a single element
//and a entire sub-array
<script>
var salary = [
   ["ABC", 24, 18000],
   ["EFG", 30, 30000],
   ["IJK", 28, 41000],
   ["EFG", 31, 28000],
]; 
  
// Prints first array
document.write("Original array :<br>");
  
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
  
document.write("<br>After removing last element " 
            + "of last inner array :<br>");
  
// Removes the last element of 3rd sub-array
salary[3].pop();
  
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
  
document.write("<br>After removing last inner array :<br>");
  
// Removes last sub-array
salary.pop();
  
for(var i = 0; i < salary.length; i++) {
    document.write(salary[i] + "<br>");
}
</script> 

Output:

Original array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31, 28000

After removing last element of last inner array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000
EFG, 31

After removing last inner array :
ABC, 24, 18000
EFG, 30, 30000
IJK, 28, 41000

My Personal Notes

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