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Observer Design Pattern in ECMAScript 6
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'use strict'; | |
// import subject from './subject/subject' | |
// import observer from './observer/observer' | |
class Subject { | |
attach(observer) { | |
this.observers.push(observer); | |
} | |
dettach(observer) { | |
for(var i in this.observers) | |
if(this.observers[i] === observer) | |
this.observers.splice(i, 1); | |
} | |
notify() { | |
for(var i in this.observers){ | |
this.observers[i].update(this); | |
} | |
} | |
} | |
class ConcreteSubject extends Subject { | |
constructor(id) { | |
super(); | |
this.id = id; | |
this.value = null; | |
this.observers = []; | |
switch (document.getElementById(id).type) { | |
case "button": { | |
document.getElementById(id).addEventListener('click', (e) => { | |
this.setValue(null); | |
}); | |
break; | |
} | |
case "text": { | |
document.getElementById(id).addEventListener('input', (e) => { | |
this.setValue(e.target.value); | |
}); | |
break; | |
} | |
case "checkbox": { | |
document.getElementById(id).addEventListener('click', (e) => { | |
this.setValue(e.target.checked); | |
}); | |
break; | |
} | |
case "radio": { | |
document.getElementById(id).addEventListener('click', (e) => { | |
this.setValue(e.target.value); | |
}); | |
break; | |
} | |
default: {} | |
} | |
} | |
getId() { | |
return this.id; | |
} | |
getValue() { | |
return this.value; | |
} | |
setValue(value) { | |
this.value = value; | |
this.notify(); | |
} | |
} | |
class Observer { | |
update(subject) {} | |
} | |
class ConcreteObserver extends Observer { | |
constructor(trigger) { | |
super() | |
this.trigger = trigger; | |
this.triggerList = []; | |
} | |
update(subject) { | |
console.log("update() : " + subject.getValue()); | |
if (this.trigger) window[this.trigger](); | |
} | |
addTrigger(trigger) { | |
this.triggerList.push(trigger); | |
} | |
} | |
class Trigger {} | |
class ConcreteTrigger extends Trigger { | |
constructor(name) { | |
this.name = name; | |
} | |
} | |
function trigger1() { | |
console.log("trigger1"); | |
}; | |
function trigger2() { | |
console.log("trigger2"); | |
}; | |
function trigger3() { | |
console.log("trigger3"); | |
}; | |
function init() { | |
var subjectIdArray = [ | |
"checkbox", "text" | |
]; | |
var observer1 = new ConcreteObserver("trigger1"); | |
var observer2 = new ConcreteObserver("trigger1"); | |
var observer3 = new ConcreteObserver(); | |
var observer4 = new ConcreteObserver(); | |
observer4.addTrigger(""); | |
var observer5 = new ConcreteObserver(); | |
var observer6 = new ConcreteObserver(); | |
var observer7 = new ConcreteObserver(); | |
var subjectButton = new ConcreteSubject("button"); | |
var subjectText = new ConcreteSubject("text"); | |
var subjectCheckbox = new ConcreteSubject("checkbox"); | |
var subjectRadio = new ConcreteSubject("radio"); | |
subjectButton.attach(observer1); | |
subjectText.attach(observer2); | |
subjectText.attach(observer3); | |
subjectCheckbox.attach(observer4); | |
subjectRadio.attach(observer5); | |
subjectRadio.attach(observer6); | |
subjectRadio.attach(observer7); | |
} |
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<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> | |
<!DOCTYPE html> | |
<html lang="en"> | |
<head> | |
<title>Observer</title> | |
<script src="<c:url value="/resources/js/init.js" />"></script> | |
</head> | |
<body> | |
<input type="button" class="input button" id="button" value="button" /> | |
<input type="text" class="input text" id="text" /> | |
<input type="checkbox" class="input checkbox" id="checkbox" /> | |
<input type="radio" class="input radio" id="radio" /> | |
<script type="text/javascript"> | |
init(); | |
</script> | |
</body> | |
</html> |
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