FlattenArray.js

flattenMap.md

/********************
** Write some code, that will flatten an array 
** of arbitrarily nested arrays of integers 
** into a flat array of integers. 
** e.g. [[1,2,[3]],4] -> [1,2,3,4]
************************/

var answer = [];

function flatten(source){
     source.map(val => Array.isArray(val)? flatten(val) : answer.push(val));
     return answer;
}
const myArray = [[1,2,[3]],4]; 
console.log(flatten(myArray)); // [1,2,3,4]