JS: Array.prototype.map
arrayX.map(f)
-
Apply function to every element of the array. Return the new array. Original array is not changed.
The function f is passed 3 args:
- currentElement
- currentIndex
- arrayX
const a1 = [3, 4, 5]; const a2 = a1.map((x) => (x + 1)); console.log(a2); // [ 4, 5, 6 ] // original is not changed console.log(a1); // [ 3, 4, 5 ]
arrayX.map(f, thisArg)
-
Use thisArg for this Binding of f. If it is not given,
undefined
is used.// example of using map with second argument function ff(x) { return [x, this]; } console.log([3, 4, 5].map(ff, 9)); // [ [ 3, 9 ], [ 4, 9 ], [ 5, 9 ] ]