Specific implementation of js preventing event appending

Home

Web Front-end

JS Tutorial

Specific implementation of js preventing event appending_javascript skills

May 16, 2016 pm 04:34 PM

Sometimes you can use e.stopPropagation(); e.preventDefault(); to prevent event bubbling and the execution of default events. But it cannot prevent the event from being added.

Under what circumstances should we prevent the addition of events?

For example:

Click "Checkout". When doing this, the checkout itself has its own event, but you must determine whether to log in before checking out.

We might write:

Js code

Copy code The code is as follows:

if(isLogin){ //Determine whether to log in
console.log("Not logged in")
}else{
//Checkout related code
}

If you click "My Homepage", there is also a login check
Login judgment code

if(isLogin){ //Determine whether to log in
console.log("Not logged in")
}else{
//Personal Center
}

If there are more logins to judge. Will there be more code like the above? Later I discovered the stopImmediatePropagation() method to prevent events from being appended. The above problem is no longer a problem.

Important: Make sure the login judgment event is the first bound event.

Demo code

Copy code The code is as follows:

<!DOCTYPE html> 

<html> 

<head lang="en"> 

<meta charset="UTF-8"> 

<title>demo</title> 

<script src="http://lib.sinaapp.com/js/jquery/1.7.2/jquery.min.js"></script> 

</head> 

<body> 

<a href="#" class="bill isLogin">Checkout </a> 

<ul> 

<li class="a1 isLogin">Add to favorites</li> 

<li class="a2 isLogin">Pay by others</li> 

<li class="a3">Add to Cart</li> 

<li class="a4 isLogin">My Homepage</li> 

</ul> 

<script> 

//Bind first 

$(".isLogin").on("click", function (e) { 

if(true){ //Login judgment 

alert("Not logged in"); 

e.stopImmediatePropagation(); 

} 

return false; 

}); 

$(".bill").on("click",function(){ 

alert("Checkout related content!"); 

}); 

$(".a1").on("click",function(){ 

alert("a1"); 

}); 

$(".a2").on("click",function(){ 

alert("a2"); 

}); 

$(".a3").on("click",function(){ 

alert("Added to cart"); 

}); 

$(".a4").on("click",function(){ 

alert("Login determination"); 

}); 

</script> 

</body> 

</html>

In fact, jquery provides us with the method $._data($('.isLogin').get(0)) to view events, open firebug and enter in the console.
Js code

$._data($('.isLogin').get(0))

You will see the following:

Js code

Object { events={...}, handle=function()}

Click to see the event array, making it easy to see what events are bound to the element.

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn