JavaScript - multiply two matrixes

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const createMatrix = (width, height, creator = () => 0) => {
    const result = new Array(height);
    for (let y = 0; y < height; ++y) {
        const row = new Array(width);
        for (let x = 0; x < width; ++x) {
            row[x] = creator(x, y);
        }
        result[y] = row;
    }
    return result;
};

const findWidth = (matrix) => {
    if (matrix.length > 0) {
        const row = matrix[0];
        if (row) {
            return row.length;
        }
    }
    return 0;
};

const findHeight = (matrix) => {
    return matrix.length;
};

const multiplyMatrixes = (a, b) => {
    const length = findWidth(a);
    if (length !== findHeight(b)) {
        throw new Error('Matrixes can not be multipled.');
    }
    const width = findWidth(b);
    const height = findHeight(a);
    const result = createMatrix(width, height);
    for (let y = 0; y < height; ++y) {
        const row = result[y];
        for (let x = 0; x < width; ++x) {
            let value = 0;
            for (let i = 0; i < length; ++i) {
                value += a[y][i] * b[i][x];
            }
            row[x] = value;
        }
    }
    return result;
};


// Usage example:

const a = [
	[1, 2],
	[4, 5],
	[7, 8]
];

const b = [
	[1, 2, 3],
	[4, 5, 6]
];

const c = multiplyMatrixes(a, b);

console.log(c);


// Output:
//
//     [ 9, 12, 15],
//     [24, 33, 42],
//     [39, 54, 69]