How to multiply elements of an array by elements from another array with the same index?

Question

I am trying to write an JS algorithm in which I have two arrays.

The value of the first one will have different numerical values. The second array will be constant, say for example [5, 3, 6, 8].

Now I would like to multiply the values from the first array, by the corresponding index value from the second array, so having for example such a first array: [3, 7, 2, 5] it would look like this: 5*3, 3*7, 6*2, 8*5.

From the result I would like to create a new array, which in this case is [15, 21, 12, 40].

How can I achieve this result?

Jaggy

Please post your algorithm, with your explanation to it and what exactly failed, so we can help you resolve it together – Accessory

Please edit your question to show what research you've done and any attempts you've made to solve the problem yourself – Blooper

Both arrays are expected to be of the same length? – Genagenappe

@Genagenappe yes, both have the same length – Jaggy

@Jaggy see if the answer below satisfy you – Genagenappe

@Genagenappe yes, I am very satisfied with this solution :) thank you very much ! – Jaggy

Answer 1

You can use map() and use the optional parameter index which is the index of the current element being processed in the array:

const arr1 = [3, 4, 5, 6];
const arr2 = [7, 8, 9, 10];

const mulArrays = (arr1, arr2) => {
    return arr1.map((e, index) => e * arr2[index]);
}

console.log(mulArrays(arr1, arr2));

This is assuming both arrays are of the same length.

Genagenappe

Answer 2

You can simply use for loop -

var arr1 = [5, 3, 6, 8];
var arr2 = [3, 7, 2, 5];
var finalArr = [];
for (var i = 0; i < arr1.length; i++) {
    finalArr[i] = arr1[i] * arr2[i];
}
console.log(finalArr);

Dogear