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JavaScript-Event Delegation

Source: Internet
Author: User
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<!DOCTYPE HTML><HTMLLang= "en"><Head>    <MetaCharSet= "UTF-8">    <title>Event delegate</title>    <style>ul{padding:20px;List-style:None;        }    </style></Head><Body>    <ulID= "ul">        <Li>111</Li>        <Li>222</Li>        <Li>333</Li>        <Li>444</Li>    </ul>    <Script>        varul=document.getElementById ('ul'); Ul.onmouseover= function(EV) {varEV=EV||window.event, Target=Ev.target||ev.srcelement; //GetEvent Source            if(Target.nodeName.toLowerCase ()== "Li") {Target.style.background= "Red"; }} ul.onmouseout= function(EV) {varEV=EV||window.event, Target=Ev.target||ev.srcelement; if(Target.nodeName.toLowerCase ()== "Li") {Target.style.background= ""; }        }    </Script></Body></HTML>

Event delegation: Use event bubbling to add events to the parent or ancestor elements to trigger the execution effect.

Benefits:

1. Improve performance.

2. Future additions to the element, the body can still trigger events.

JavaScript-Event Delegation

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