Array.prototype.flatMap & Array.prototype.flattenStage -1 Draft / February 9, 2016 Array.prototype.flatMap & Array.prototype.flatten Introduction # Array.prototype.flatten returns a new array that is one dimensional with all sub-array elements concatted into it recursively. Array.prototype.flatMap first maps each element using a mapping function, then flattens the result into a new array. It is identical to a map followed by a flatten, but flatM
