Notes-JavaScript events

MW-event advanced application 1

Event binding:

Object. onclick = function () {alert (this) ;}// returns the current object

Object. attachevent ('onclick', function () {alert (this );})
// Return the window object. The bug in IE points to the window object.

Object. addeventlistener ('click', function () {alert (this) ;}, false );
// Returns the current object

Event binding and anonymous functions:

Declare an AAA function first;

Object. attachevent ('onclick', AAA );

Object. detachevent ('onclick', AAA); // unbound

Anonymous functions:

Object. attachevent ('onclick', function () {alert ('A ');});

Object. detachevent ('onclick', function () {alert ('A ');});
// The contact binding fails.

The reason is: each time an anonymous function is used, a new function will be created. Even if the function looks the same, they still have two functions, so the unbinding above is unsuccessful. You can see:

VaR A = function () {alert ('A ');};

VaR B = function () {alert ('A ');};

Alert (A = B); // return false, that is, the two anonymous functions are not the same thing. In fact, two different functions are created, as shown below:

VaR A = new function ('alert ("")');

VaR B = new function ('alert ("")');