Multiple choice box full use addEvenListener achieve

The first step, since it is multiple choice and select all, then you need to click the mouse, so I tried to get their id, respectively, and then add them to the click event

          　// Get the id box full of 
  　　　　　　var allCheck = document.getElementById ( "allCheck" ); 
　　　　　　　// add a click event
            allCheck.addEventListener ( "the Click" , the clickHandler); 
　　　　　　　// get additional selection frame ID
             for ( var I =. 1; I <. 5; I ++ ) {
                 var Check = document.getElementById ( "Check" + I); 
　　　　　　　　　　// add click the event
                 the this .addEventListener ( "the click" , clickHandler);
            }

 The second step, to perform this function click event

function the clickHandler (E) { 
　　　　　　　　　　// Analyzing this box is not full
                 IF ( the this == allCheck) {
                     for ( var I =. 1; I <. 5; I ++ ) {
                         var Check = document.getElementById ( "Check" + I) ;
                        check.checked = allCheck.checked;
                    }
                }
                var bool = true;
                for(var i = 1; i < 5;i++){
                    var check = document.getElementById("check"+i);
                    if(!check.checked)
                     bool = false;
                }
                allCheck.checked =bool;
            }

effect: