Element.Event

Posted 2022-06-22 michael_yqs

addEvent(type,fn)：为DOM元素增加一个事件监听器

removeEvent(type,fn):移除先前为DOM元素添加的事件监听器 

eg:

var destroy = function() alert('Boom: ' + this.id);  // this refers to the Element.
$('myElement').addEvent('click', destroy);
 
//later...
$('myElement').removeEvent('click', destroy);

addEvents(events):一次为一个DOM元素添加多个事件监听器

eg:

$('myElement').addEvents(
    mouseover: function()
        alert('mouseover');
    ,
    click: function()
        alert('click');
    
);

removeEvents(events):移除DOM元素上某个类型的事件的所有监听器

var myElement = $('myElement');
myElement.addEvents(
    mouseover: function()
        alert('mouseover');
    ,
    click: function()
        alert('click');
    
);
 
myElement.addEvent('click', function() alert('clicked again'); );
myElement.addEvent('click', function() alert('clicked and again :('); );
//addEvent will keep appending each function.
//Unfortunately for the visitor, there will be three alerts they'll have to click on.
myElement.removeEvents('click'); // saves the visitor's finger by removing every click event.

fireEvent(type[,param,delay]):执行一个DOM元素上某个类型的事件的所有监听器，多用于需要在特定的时间或者场合下触发事件时

eg1:

function test(a) 
  console.log(a);

$("btn1").addEvent('click', test);
$("btn1").addEvent('click', function() 
  console.log('btn1 click event run')
);

$("btn1").fireEvent("click", "hello,world");

这个例子中代码将在页面一加载完就执行，而不需要等到click btn1时才执行。下面这个例子将更好的说明fireEvent的使用场合：

textarea.addEvents(
    focus: function() 
      // When focusing, if the textarea contains value "Type here", we
      // simply clear it.
      if (textarea.value.contains('Type here')) textarea.set('value', '');
    ,

    keyup: function() 
      // When user keyups we check if there are any of the magic words.
      // If yes, we fire our custom event burn with a different text for each one.
      if   (textarea.value.contains('hello')) textarea.fireEvent('burn', 'hello world!');
      else if (textarea.value.contains('moo')) textarea.fireEvent('burn', 'mootools!');
      else if (textarea.value.contains('pizza')) textarea.fireEvent('burn', 'Italy!');
      else if (textarea.value.contains('burn')) textarea.fireEvent('burn', 'fireEvent');
      // note that in case of 'delayed', we are firing the event 1 second late.
      else if (textarea.value.contains('delayed')) textarea.fireEvent('burn', "I'm a bit late!", 1000);
    ,
    burn: function(text) 
      // When the textarea contains one of the magic words
      // we reset textarea value and set the log with text
      textarea.set('value', '');
      log.set('html', text);
      // then we start the highlight morphing
      highlight.start(
        backgroundColor: ['#fff36f', '#fff'],
        opacity: [1, 0]
      );
    
  );

注意标红部分。

结合这两个例子，想必fireEvent的用法已经很清楚了。

cloneEvent（from[,type]）：从一个DOM元素上复制所有监听器到本元素：

eg：

function test(a) 
  console.log(a);

$("btn1").addEvent('click', test);
$("btn1").addEvent('click', function() 
  console.log('btn1 click event run')
);
$("btn1").fireEvent("click", 123);
$("btn2").cloneEvents($("btn1"));

将btn1上绑定的事件复制给btn2