View difference between Paste ID: ketBkx9m and 04m4URYL

 (() => {
 
   String.prototype.ensureStart = function(str = '') {
     if (!this.startsWith(str)) {
       return str + this;
     }
 
     return this.toString();
   }
 
   String.prototype.ensureEnd = function(str = '') {
     if (!this.endsWith(str)) {
       return this + str;
     }
 
     return this.toString();
   }
 
   String.prototype.isEmpty = function() {
     return this.length == 0;
   }
 
 
   String.prototype.truncate = function(n) {
     if (n < 4) {
       return '.'.repeat(n);
     }
 
     if (this.length < n) {
       return this.toString;
     }
 
     let foundedSpace = this.lastIndexOf(' ');
 
     if (foundedSpace != -1) {
       return str.substring(0,foundedSpace) + '...';
     } else {
       return str.substring(0, n - 3 ) + '...';
     }
   }
 
   String.format = function(str, ...params) {
       params.forEach((key, index) => {
         str = str.replace(`{${index}}`, key);
       })
   }
 
 })();