math.js

function divide(x, y) {
    if (y === 0) {
        throw new Error('Division by zero');
    }
    var xabs = x < 0 ? -x : x;
    var yabs = y < 0 ? -y : y;
    var result = 0;
    while (xabs >= yabs) {
        result++;
        xabs -= yabs;
    }

    if ((x < 0 && y < 0) || (x > 0 && y > 0)) {
        return result;
    }
    return -result;
}

function multiply(x, y) {
    var result = 0;
    var count = y < 0 ? -y : y;
    for (var i = 0; i < count; i++) {
        if (y > 0) {
            result += x;
        } else {
            result -= x;
        }

    }
    return result;
}