JavaScript: Number of arrays inside an array

JavaScript Array: Exercise-53 with Solution

Count Arrays Inside Array

Write a JavaScript program to count the number of arrays inside a given array.

Test Data:

([2,8,[6],3,3,5,3,4,[5,4]]) -> 2
([2,8,[6,3,3],[4],5,[3,4,[5,4]]]) -> 3

Sample Solution:

JavaScript Code-1:

// Function to count the number of arrays inside an array
function test(arr_nums){
    // Use filter to create an array containing only the arrays from the input array
    return arr_nums.filter(n => Array.isArray(n)).length;
}

// Test the function with an array containing nested arrays
arr_nums = [2, 8, [6], 3, 3, 5, 3, 4, [5, 4]];
console.log("Number of arrays inside the said array: " + test(arr_nums));

// Test the function with another array containing nested arrays
arr_nums = [2, 8, [6, 3, 3], [4], 5, [3, 4, [5, 4]]];
console.log("Number of arrays inside the said array: " + test(arr_nums));

Output:

Number of arrays inside the said array: 2
Number of arrays inside the said array: 3 

Flowchart :

Live Demo :

See the Pen javascript-array-exercise-53 by w3resource (@w3resource) on CodePen.

JavaScript Code-2:

// Function to count the number of non-empty arrays inside an array
function test(arr_nums){
    // Use filter to create an array containing only non-empty arrays from the input array
    return arr_nums.filter(n => n.length).length;
}

// Test the function with an array containing nested arrays
arr_nums = [2, 8, [6], 3, 3, 5, 3, 4, [5, 4]];
console.log("Number of non-empty arrays inside the said array: " + test(arr_nums));

// Test the function with another array containing nested arrays
arr_nums = [2, 8, [6, 3, 3], [4], 5, [3, 4, [5, 4]]];
console.log("Number of non-empty arrays inside the said array: " + test(arr_nums));

Output:

Number of arrays inside the said array: 2
Number of arrays inside the said array: 3 

Flowchart :

Live Demo :

See the Pen javascript-array-exercise-53-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that traverses an array and counts how many elements are arrays using Array.isArray().
• Write a JavaScript function that uses reduce() to count nested arrays within a parent array.
• Write a JavaScript function that iterates through an array and recursively counts arrays only at the top level.
• Write a JavaScript function that validates the input to ensure it is an array and returns zero if it is not.

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