JavaScript Advanced Programming Second Edition Chapter 12 Summary of Event Key Points (Commonly Used Cross-Browser Detection Methods)_Javascript Skills

var EventUtil={ //Cross-browser handler --- Create Method
addHandler:function(element,type,handler){
if(element.addEventListener){
element.addEventListneter(type,handler,false);
}else if(element.attachEvent) {
element.attachEvent("on" type,handler);
}else{
element["on" type]=handler;
}
}
removeHandler:function( element,type,handler){ //Cross-browser handler---removal method
if(element.removeEventListener){
element.removeEventListneter(type,handler,false);
}else if( element.detachEvent){
element.detachEvent("on" type,handler);
}else{
element["on" type]=handler;
}
}
getEvent:function(event){ //Cross-browser event object---return a reference to the event object
return event?event:window.event;
}
getTarget:function(event){ // Cross-browser event object---return the target of the event
return event.target||event.srcElement;
}
preventDefault:function(event){ //Cross-browser event object---cancel Default event
if(event.preventDefault){
event.preventDefault();
}else{
event.returnValue=false;
}
}
stoppropagation:function (event){ //Cross-browser event object---block event flow
if(event.stoppropagation){
event.stoppropagation();
}else{
event.canceBubble=false ;
}
}
getRelatedTarget:function(event){ //Get related elements across browsers
if(event.relatedTarget){
return event.relatedTarget;
}else if(event.toElement){
return envent.toElement;
}else if(event.fromElement){
return event.fromElement;
}else{
return null;
}
}
getButton:function(event){ //button attribute detection of mouse event
if(document.implementation.hasFeature("MouseEvent","2.0")){
return event. button;
}else{
switch(event.button){
case 0:
case 1:
case 3:
case 5:
case 7:
return 0;
case 2:
case 6:
return 2
case 4:
return 1
}
}
}
getCharCode:function (event){ //Cross-browser character encoding---charCode attribute detection
if(typeof event,charCode=="number"){
return event.charCode;
}else{
return event.keyCode;
}
}
}