Nodejs Utililty Methods String Empty Check

String.prototype.isEmpty = function() {
   return (this.length === 0 || !this.trim());
Array.prototype.appendStringToElementAtIndex = function(index, str) {
    if(typeof this[index] === 'undefined' || typeof this[index] !== 'string') return false;
    this[index] += ' ' + str;
};

String.prototype.isEmpty = function() {
    return (this.length === 0 || !this.trim());
};

String.prototype.isEmpty = function(){
    if(typeof this !== 'string') {
        if(typeof this === 'object' && !(this instanceof String)){
            throw {
                name: 'InvalidType',
                message: 'The current type is not a String'
    return this.length === 0;
};

String.prototype.isEmpty = function() {
  var rtn = (this == null || this == undefined || this.trim() == '');
  return rtn;
};

String.prototype.isEmpty = function(pattern) {
  return this == '';
};

String.isEmpty = function(str){
    if(typeof str === 'string'){
        str = str.trim();
    switch(str){
        case "":
        case 0:
        case null:
        case false:
...

String.prototype.isBlank = function() { 
  return !this.match(/\S/) 

String.prototype.isBlank = function() {
  return (!this || /^\s*$/.test(this));
};

String.prototype.isBlank = function() {
    return (this==null || this=="");

String.prototype.isBlank = function (){
  var str = $.trim(this);
  if(str == "") {
    return true;
  } else {
    return false;