javascript-code/JavaScript-Design-Patterns/The-Observer-Pattern/5 - Event listeners are also observers.js at master · rockhe168/javascript-code · GitHub

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// example using listeners

var element = document.getElementById(‘a’);

var fn1 = function(e) {

// handle click

};

var fn2 = function(e) {

// do other stuff with click

};

// 使用事件监听器，所以click事件发生时fn1和fn2都会被调用

addEvent(element, ‘click’, fn1);

addEvent(element, ‘click’, fn2);

// example using handlers

var element = document.getElementById(‘b’);

var fn1 = function(e) {

// handle click

};

var fn2 = function(e) {

// do other stuff with click

};

// 使用事件处理器，onclick事件发生时只会调用fn2

element.onclick = fn1;

element.onclick = fn2;