Nodejs Utililty Methods Number Calculate

Number.prototype.concat = Number.prototype.concat || function (value) {
  let number = this;
  let digits = exports.digitLength(value);
  number *= Math.pow(10, digits);
  return number + value;
};

Number.prototype.cos = function() {
    return Math.cos(this);

Number.prototype.countDecimals = function () {
    if(Math.floor(this.valueOf()) === this.valueOf()) return 0;
    return this.toString().split(".")[1].length || 0; 

Number.prototype.to_s       = function(){ return toString(this)     }
Number.prototype.to_i       = function(){ return parseInt(this, 10) }
Number.prototype.is_string  = function(){return false}
Number.prototype.is_hash    = function(){return false}
Number.prototype.is_array   = function(){return false}
Number.prototype.is_number  = function(){return true}
Number.prototype.decimal = function(nb) {
    if( this.toString().indexOf('.') === false ) return this ;
    m = Math.pow(10, nb) ;
...

Number.prototype.decimalPlaces = function(digits) {
    var re = new RegExp("(\\d+\\.\\d{" + digits + "})(\\d)"),
        m = this.toString().match(re);
    return m ? parseFloat(m[1]) : this.valueOf();
};

Number.prototype.decorateFloat = function (decimals, decSeparator) {
  if(decSeparator == undefined)
    decSeparator = '.';
  var price = this;
  var decPattern = '';
  for(var i = 0; i < decimals; i++)
    decPattern += '0';
  price = price.roundFloat(decimals);
  var split = price.toString().split('.');
...

Number.prototype.digits = function() {
    return (Math.floor(this)+"").replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");
};

Number.prototype.discountPercentage = function(val){
  return this - this.percentage(val);
};

Number.prototype.div10 = function () {
  return this/10;
Object.prototype.say = function (s) {
 console.log('I say ' + s);
var o = {};
o.say("Hello");
var n = 120;
...

Number.prototype.double = function() {
  return this * 2;
};