SOURCE

function subNum(arg1, arg2) {
    var re1, re2, m, n;
    try {
        re1 = arg1.toString().split(".")[1].length;
    } catch (e) {
    re1 = 0;
    }
    try {
        re2 = arg2.toString().split(".")[1].length;
    } catch (e) {
        re2 = 0;
    }
    m = Math.pow(10, Math.max(re1, re2)); 
    n = (re1 >= re2) ? re1 : re2;
    return ((arg1 * m - arg2 * m) / m).toFixed(n);
}

console.log(subNum(1.43854,2.00001))