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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,
//  selects 1st row, and  selects the 3rd element
// of that 1st row which is 18000
salary;

// Similarly,
salary; // 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 = "India";

// It adds "India" at the 4th index of 4th sub-array,
// If we print the entire 4th sub-array, document.write(salary);
// the output will be :  ["EFG", 31, 28000, "India"]
// indexing starts from 0```
• We can use push() method to add elements in the array.
```salary.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);
// 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.pop();

// Removes last sub-array
// That is "["EFG", 31, 28000]"
salary.pop();
```
• Example 1:
 `// Prints a simple multidimensional array in JavaScript```

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``                    `

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``                    `

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`` `

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
EFG, 31, 28000, India```
• Example 5:
 `// Prints a simple multidimensional array in``// JavaScript where we add a new inner array `` `

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`` `

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```
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