Sort 2D array in JavaScript -

i'm trying sort numbers in each array greatest smallest, first 1 being sorted. need nested loop? i'm stuck.

function sortnums(arr) {   for(var = 0; < arr.length; i++){      arr[i] = arr[i].sort(function(a, b){return b-a;});      return arr;    } }  sortnums([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]); 

when using return keyword function terminated. move outside iteration , should good:

function sortnums(arr) {   for(var = 0; < arr.length; i++) {      arr[i] = arr[i].sort(function(a, b) {        return b - a;      });   }   return arr; }  sortnums([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);