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Javascript supports event listening encapsulation of anonymous Functions

Source: Internet
Author: User
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In js, The addEventListener and attachEvent functions are used for event listening. In jquery, the $ (# id) function is almost the same. Next we will see that an event listening function supports anonymous functions, I hope to help you.

There are a lot of scenarios for event listening in js. It is nothing more than determining whether the browser supports addEventListener and attachEvent. There are many methods to search for event listening on the Internet, but there are still some incomplete methods. In the following method, the method for adding event listening is the same, but a point operation is performed on the unbinding event. Now anonymous functions can be used, therefore, when binding events, you no longer need to name functions separately.

First look at the demo:

 

The Code is as follows: Copy code

<! DOCTYPE html>
<Html>
<Head profile = "http://www.bKjia. c0m">
<Meta charset = "UTF-8">
<Title> grid </title>
<Style>
Html, body {width: 100%; height: 100%; margin: 0; padding: 0 ;}
Div {padding: 0; margin: 0; font-size: 14px ;}
# Wrap {height: 300px; border: 5px dotted # ccc; background: # ececec; color: # aaa; font-size: 50px; text-align: center; line-height: 300px ;}
. Btn {width: 200px; height: 30px; display: inline-block; text-align: center; line-height: 30px; border: 2px solid # ccc; background: # ececec; margin: 10px; text-decoration: none; color: #333 ;}
. Btn: hover {background: # ddd ;}
</Style>

</Head>
<Body>

<Div id = "wrap">
Click here
</Div>

<A onclick = "bindFn ()" href = "javascript:;" class = "btn"> bind events </a>
<A onclick = "unbindFn ()" href = "javascript:;" class = "btn"> unbind events </a>

<Script>

/* Bind events and unbind events */
Var handleHash = {};
Var bind = (function (){
If (window. addEventListener ){
Return function (el, type, fn, capture ){
El. addEventListener (type, function (){
Fn ();
HandleHash [type] = handleHash [type] | [];
HandleHash [type]. push (arguments. callee );
}, Capture );
};
} Else if (window. attachEvent ){
Return function (el, type, fn, capture ){
El. attachEvent ("on" + type, function (){
Fn ();
HandleHash [type] = handleHash [type] | [];
HandleHash [type]. push (arguments. callee );
});
};
}
})();
Var unbind = (function (){
If (window. addEventListener ){
Return function (el, type ){
If (handleHash [type]) {
Var I = 0, len = handleHash [type]. length;
For (I; I <len; I + = 1 ){
El. removeEventListener (type, handleHash [type] [I]);
}
};
};
} Else if (window. attachEvent ){
Return function (el, type ){
If (handleHash [type]) {
Var I = 0, len = handleHash [type]. length;
For (I; I <len; I + = 1 ){
El. detachEvent ("on" + type, handleHash [type] [I]);
}
};
};
}
})();


Var obj = document. getElementById ('wrapp ');
Function bindFn (){
Bind (obj, 'click', function (){
Alert ('click ');
});
Bind (obj, 'click', function (){
Alert ('click2 ');
});
};
Function unbindFn (){
Unbind (obj, 'click ');
};

</Script>
</Body>
</Html>

Code Analysis

Main Code:

The Code is as follows: Copy code
/* Bind events and unbind events */
Var handleHash = {};
Var bind = (function (){
If (window. addEventListener ){
Return function (el, type, fn, capture ){
El. addEventListener (type, function (){
Fn ();
HandleHash [type] = handleHash [type] | [];
HandleHash [type]. push (arguments. callee );
}, Capture );
};
} Else if (window. attachEvent ){
Return function (el, type, fn, capture ){
El. attachEvent ("on" + type, function (){
Fn ();
HandleHash [type] = handleHash [type] | [];
HandleHash [type]. push (arguments. callee );
});
};
}
})();
Var unbind = (function (){
If (window. addEventListener ){
Return function (el, type ){
If (handleHash [type]) {
Var I = 0, len = handleHash [type]. length;
For (I; I <len; I + = 1 ){
El. removeEventListener (type, handleHash [type] [I]);
}
};
};
} Else if (window. attachEvent ){
Return function (el, type ){
If (handleHash [type]) {
Var I = 0, len = handleHash [type]. length;
For (I; I <len; I + = 1 ){
El. detachEvent ("on" + type, handleHash [type] [I]);
}
};
};
}
})();

Principle Analysis:

HandleHash is used to cache events in the hash table. handleHash ['event name'] is an array to add multiple event listening methods, when unbind events, traverse the array of handleHash ['event name'] And then remove it.

Usage:

The Code is as follows: Copy code

Bind (obj, 'click', function (){
Alert ('click ');
});
Unbind (obj, 'click ');

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Related Keywords:
anonymous function javascript example javascript anonymous array javascript anonymous function parameters javascript anonymous function javascript onclick event mousedown event javascript event bubbling javascript
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