Prevent events from bubbling up

JavaScript stops bubbling and blocks browser default behavior

Event compatible

Js code

function myfn(e){

var evt = e ? e:window.event;

}

js stop Bubble

Js code

function myfn(e){

window.event? window.event.cancelBubble = true : e.stopPropagation();

}

js prevent default behavior

Js Code cFunction Myfn (E) {

Window.event? Window.event.returnValue = false: e.preventDefault (); ), IE uses e.cancelBubble = true.

stopPropagation is also a method of the event object (Event). Its function is to prevent the bubbling event of the target element, but it will not prevent the default behavior.

js prevents default behavior:

w3c’s method is e.preventDefault(), IE uses e.returnValue = false;

preventDefault is a method of the event object (Event), and its function is to cancel the default of a target element Behavior.
Since we are talking about default behavior, of course the element must have a default behavior before it can be canceled. If the element itself does not have a default behavior, the call will of course be invalid.

What elements have default behaviors? Such as link , submit button , etc.
When the event object's cancelable is false, it means there is no default behavior. Even if there is a default behavior, calling preventDefault will not work.

return false:
javascript's return false will only prevent the default behavior, but using jQuery will both prevent the default behavior and prevent the object from bubbling.

Summary of usage:
When you need to stop the bubbling behavior, you can use


Js code

function stopBubble(e) {

//If the event object is provided, this is a non-IE browser

if (e && e.stopPropagation)

//So it supports W3C’s stopPropagation() method

e.stopPropagation();

else

//Otherwise, we need to use IE to cancel event bubbling

window.event.cancelBubble = true;

}

When you need to prevent the default behavior, you can use:

Js code

//Block the browser’s default behavior

function stopDefault(ee){

//Prevent default browser action (W3C)

if (e && e.preventDefault)

e.preventDefault();

//How to prevent the default action of function in IE

else

 window.event .returnValue = false;

return false;

}

Event Notes:

event represents the status of the event, such as the element that triggered the event object, the position and status of the mouse, the key pressed, etc.;

The event object is only valid during the event.

The events in firefox are different from those in IE. The ones in IE are global variables and can be used at any time;

The events in firefox can only be used when guided by parameters, and they are temporary variables at runtime.

In IE/Opera it is window.event, in Firefox it is event;

The object of the event is window.event.srcElement in IE,
In Firefox it is event.target, both are available in Opera.

The following two sentences have the same effect:


Js code

//code from http://caibaojian.com/javascript-stoppropagation-preventdefault.html

function a(e){

var e = (e) ? e : ((window.event) ? window.event : null);

var e = e || window.event; // window.event is null under firefox, event is null under IE

}