How do I multiply each member of an array by a scalar in javascript?

Question

For example, how do I achieve the following without iterating over the array?

var a = [1, 2, 3] * 5;  // a should equal [5, 10, 15]

Answer 1

As stated in Docs:

The map() method creates a new array with the results of calling a provided function on every element in the calling array.

In my opinion, .map() is more suitable if someone wants to create a new array based on input values from the current array.

However, if someone wants to modify the array in place, .forEach() seems a better choice.

In ES6 we may use:

• Array.prototype.forEach()
• Arrow functions

Following code will modify a given array arr in place (without creating a new one):

arr.forEach((value, index) => {arr[index] *= 5});

Demo:

var arr = [1, 2, 3];
var scalar = 5;

arr.forEach((value, index) => {
    arr[index] *= scalar;
});
console.log(arr);