How to use JavaScript attachevent and addeventlistener

Attachevent method button onclick
Addeventlistener method button click
The usage principle of the two is as follows: the priority of the execution can be different. The example below is as follows:
The attachevent method attaches other processing events to an event. (Mozilla series not supported)
The addeventlistener method is used in the Mozilla series.
Example:
Java Code Copy code The Code is as follows: Document. getelementbyid ("BTN"). onclick = Method1;
Document. getelementbyid ("BTN"). onclick = method2;
Document. getelementbyid ("BTN"). onclick = method3;

If this is the case, only medhot3 will be executed.
Write as follows:
Java code:Copy codeThe Code is as follows: var btn1obj = Document. getelementbyid ("btn1 ");
// Object. attachevent (event, function );
Btn1obj. attachevent ("onclick", Method1 );
Btn1obj. attachevent ("onclick", method2 );
Btn1obj. attachevent ("onclick", method3 );

The execution sequence is method3-> method2-> Method1
If the Mozilla series does not support this method, you need to use addeventlistener.
Java code:Copy codeThe Code is as follows: var btn1obj = Document. getelementbyid ("btn1 ");
// Element. addeventlistener (type, listener, usecapture );
Btn1obj. addeventlistener ("click", Method1, false );
Btn1obj. addeventlistener ("click", method2, false );
Btn1obj. addeventlistener ("click", method3, false );

The execution sequence is Method1-> method2-> method3
Instance used:
1. Java code:Copy codeThe Code is as follows: var El = editform_document.body;
// Get the object first. editform_document is actually an IFRAME
If (El. addeventlistener )...{
El. addeventlistener ('click', kinddisablemenu, false );
} Else if (El. attachevent )...{
El. attachevent ('onclick', kinddisablemenu );
}

2. Java code:Copy codeThe Code is as follows: if (window. addeventlistener ){
Window. addeventlistener ('load', _ Uco, false );
} Else if (window. attachevent ){
Window. attachevent ('onload', _ Uco );
}