Convert a 2D JavaScript array to a 1D array [duplicate]

Question

I want to convert a 2D JavaScript array to a 1D array, so that each element of the 2D array will be concatenated into a single 1D array.

Here, I'm trying to convert arrToConvert to a 1D array.

var arrToConvert = [[0,0,1],[2,3,3],[4,4,5]];  console.log(get1DArray(arrToConvert)); //print the converted array  function get1DArray(2dArr){     //concatenate each element of the input into a 1D array, and return the output     //what would be the best way to implement this function? } 

Answer 1

Use the ES6 Spread Operator

arr1d = [].concat(...arr2d); 

Note that this method is only works if arr2d has less than about 100 000 subarrays. If your array gets larger than that you will get a RangeError: too many function arguments.

For > ~100 000 rows

arr = []; for (row of table) for (e of row) arr.push(e); 

concat() is too slow in this case anyway.

The Underscore.js way

This will recursively flatten arrays of any depth (should also work for large arrays):

arr1d = _.flatten(arr2d); 

If you only want to flatten it a single level, pass true as the 2nd argument.

A short < ES6 way

arr1d = [].concat.apply([], arr2d);