Array Flatten in JavaScript

Flattening arrays is one of those concepts that shows up everywhere—from real-world coding tasks to technical interviews. In JavaScript, flattening an array refers to converting a nested (multi-dimensional) array into a single-level array by extracting all sub-elements. What nested arrays are Nested arrays, also known as multi-dimensional arrays, are arrays that contain other arrays as elements. They represent hierarchical data, such as a grid, tree-like structures, or complex API responses. Example: const nestedArray = [ 1 , [ 2 , 3 ], [ 4 , [ 5 , 6 ]]]; Visual Representation : [ 1 , [ 2 , 3 ], [ 4 , [ 5 , 6 ] ] ] Tree view : [] / | \ 1 [] [] / \ / \ 2 3 4 [] / \ 5 6 Why flattening arrays is useful Flattening converts a nested array into a single-level array. Data Normalization: Converts complex tree-like structures from API responses into simple lists for easier processing. Simplified Manipulation: Operations like sorting, searching, or mapping are significantly easier on a flat arra