// Single and multi line comments.
                              
                            
                          
                          

                            

                              
                                // this is an example of a single line comment.
                              
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              
                                /*
                              
                            
                          
                          

                            

                               * this is an example
                            
                          
                          

                            

                               * of a
                            
                          
                          

                            

                               * multi line
                            
                          
                          

                            

                               * comment.
                            
                          
                          

                            

                               */
                            
                          
                        

                          

                            

                              
                                // Whitespace is insignificant.
                              
                            
                          
                          

                            

                              var hello = "Hello";
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              var world     =      "World!";
                            
                          
                        

                          

                            

                              
                                // Semantic whitespace promotes readability.
                              
                            
                          
                          

                            

                              
                                // Readable code is good!
                              
                            
                          
                          

                            

                              var foo = function() {
                            
                          
                          

                            

                               
                            
                          
                          

                            

                                for ( var i = 0; i < 10; i++ ) {
                            
                          
                          

                            

                               
                            
                          
                          

                            

                                  alert( i );
                            
                          
                          

                            

                               
                            
                          
                          

                            

                                }
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              };
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              foo();
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              
                                // This is much harder to read!
                              
                            
                          
                          

                            

                              var foo=function() {for(var i=0;i<10;++){alert(i);}};foo();
                            
                          
                        

                          

                            

                              
                                // Valid identifier names.
                              
                            
                          
                          

                            

                              var myAwesomeVariable = "a";
                            
                          
                          

                            

                              var myAwesomeVariable2 = "b";
                            
                          
                          

                            

                              var my_awesome_variable = "c";
                            
                          
                          

                            

                              var $my_AwesomeVariable = "d";
                            
                          
                          

                            

                              var _my_awesome_variable_$ = "e";