DEV Community

Cover image for Flattening Arrays In Javascript
karthik raji
karthik raji

Posted on

Flattening Arrays In Javascript

It was always complicated to flatten an array in #JavaScript. Not anymore! ES2019 introduced a new method that flattens arrays.

The Main purpose of Flattening Arrays is to convert multi dimensional array to single dimensional array.(2d or 3D to 1D array)

The flat() method is an inbuilt array method that flattens a given array into a newly created one-dimensional array. It concatenates all the elements of the given multidimensional array, and flats upto the specified depth. We can specify the depth limit to where we need to flatten the array. By default, the depth limit is 1.

Alt Text
older Ways of flatting an array

var arrays = [["$6"], ["$12"], ["$25"], ["$25"], ["$18"], ["$22"], ["$10"], ["$0"], ["$15"],["$3"], ["$75"], ["$5"], ["$100"], ["$7"], ["$3"], ["$75"], ["$5"]];
es
It can be best done by javascript reduce function.

arrays = arrays.reduce(function(a, b){
return a.concat(b);
}, []);

Or, with ES2015:

arrays = arrays.reduce((a, b) => a.concat(b), []);

Alt Text

latest way of doing(2019)
Alt Text

const arr1 = [1, 2, [3, 4]];
arr1.flat();
// [1, 2, 3, 4]

const arr2 = [1, 2, [3, 4, [5, 6]]];
arr2.flat();
// [1, 2, 3, 4, [5, 6]]

// Flatten 2 levels deep
const arr3 = [2, 2, 5, [5, [5, [6]], 7]];
arr3.flat(2);
// [2, 2, 5, 5, 5, [6], 7];

// Flatten all levels
const arr4 = [2, 2, 5, [5, [5, [6]], 7]];
arr4.flat(Infinity);
// [2, 2, 5, 5, 5, 6, 7];

Thanks !!Happy coding

Top comments (0)