JavaScript:The Class of an Object

Blackbaby

function is(type, obj) {     var clas = Object.prototype.toString.call(obj).slice(8, -1);     return obj !== undefined && obj !== null && clas === type; }  is('String', 'test'); // true is('String', new String('test')); // true  
 
   In the above example, Object.prototype.toString gets called with the value of this being set to the object whose [[Class]] value should be retrieved.