Manipulating Vectors of Numbers in JavaScript

vectors.js

'use strict';

const getVectorSize = vector => Math.sqrt(
    vector.map(n => Math.pow(n, 2))
	.reduce((total, n) => total + n, 0)
);

const addVectors = (a, b) => a.map((number, i) => number + b[i]);
const multiplyVectors = (a, b) => a.map((number, i) => number * b[i]);

const multiplyVector = (vector, operand) => (
    vector.map(number => number * operand)
);

const getDotProduct = (a, b) => a.reduce((result, number, i) => (
    result + (number * b[i])
), 0);

const getScalarProjection = (a, b) => (
    getDotProduct(a, b) / getVectorSize(a)
);

const getVectorProjection = (aVector, bVector) => (
    aVector.map(
        a => getScalarProjection(aVector, bVector) * (a / getVectorSize(aVector))
    )
);

// assumes basis vectors are orthogonal
const getFromBasis = (vector, ...basisVectors) => (
    basisVectors.map(basisVector => (
        getDotProduct(vector, basisVector) / (getVectorSize(basisVector) ** 2)
    ))
);

const getCos = (a, b) => (
    getDotProduct(a, b) / (getVectorSize(a) * getVectorSize(b))
);

// [1.2, -1.6, 0]
console.log(getVectorProjection([3, -4, 0], [10, 5, -6]));

// 0
console.log(getCos([2, 1], [-2, 4]));

// [1, 0, 1, 1]
console.log(
    getFromBasis(
        [1, 1, 2, 3],
        [1, 0, 0, 0],
        [0, 2, -1, 0],
        [0, 1, 0, 0],
        [0, 0, 0, 3]
    )
);