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JavaScript - Using concat() on sparse arrays
By IncludeHelp Last updated : January 20, 2024
In JavaScript, a sparse array is an array in which the elements do not have contiguous indexes starting at 0.
Problem statement
Given two Sparse arrays, we have to add them and check what will be the result of the concatenated array.
Concatenating sparse arrays
To concatenate two sparse arrays, use Array.concat() method, the concat() method also returns a sparse array if the inputs are sparse arrays.
JavaScript code to concatenate two sparse arrays
The following example concatenates two sparse arrays arr1 and arr2.
// creating two sparse arrays
const arr1 = [1, , 3];
const arr2 = [4, , 5, 6, , 7];
// concatenating sparse arrays
const result = arr1.concat(arr2);
// printing arrays
console.log("arr1:", arr1);
console.log("arr2:", arr2);
console.log("result:", result);
Output
The output of the above code is:
arr1: [1, empty, 3]
arr2: [4, empty, 5, 6, empty, 7]
result: [1, empty, 3, 4, empty, 5, 6, empty, 7]
To understand the above example, you should have the basic knowledge of the following JavaScript topics: