Summary of main event points in Chapter 12th of javascript advanced programming (common cross-browser detection methods)

Copy codeThe Code is as follows:
Var EventUtil = {// cross-browser handler --- Creation 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 --- Delete 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 the reference of the event object
Return event? Event: window. event;
}
GetTarget: function (event) {// cross-browser event object --- return the event Target
Return event.tar get | 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 stream
If (event. stoppropagation ){
Event. stoppropagation ();
} Else {
Event. canceBubble = false;
}
}
GetRelatedTarget: function (event) {// cross-browser retrieval of Related Elements
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 for mouse events
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;
}
}
}

Event delegation: a solution with too many Event Handlers reduces memory and improves performance;
Simulated Event: This is complicated and requires further research;