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单例模式.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>单例模式</title>
</head>
<body>
<p>单例模式定义：确保只有一个实例，并提供一个访问它的全局访问点。</p>
<p>JavaScript中，在合适的时候才创建对象，并且只创建唯一的一个。</p>
<p>用到知识点：闭包，高阶函数。</p>
<p>将管理单例的职责和创建对象分布在两个不同的方法中，可以重复使用。</p>
<button id="addBtn">Login</button>
<button id="addBtn2">Login2</button>
<script type="text/javascript">
var getSingle = function (fn) {
var result;
return function() {
return result || (result = fn.apply(this, arguments));
}
};
var createLoginLayer = function() {
var div = document.createElement('div');
div.innerHTML = 'I am login window';
div.style.display = 'none';
document.body.appendChild(div);
return div;
};
var createSingleLoginLayer = getSingle(createLoginLayer);
document.getElementById('addBtn').onclick = function() {
var loginLayer = createSingleLoginLayer();
loginLayer.style.display = 'block';
};
var createLoginLayer2 = function() {
var div = document.createElement('div');
div.innerHTML = 'I am login window 2';
div.style.display = 'none';
document.body.appendChild(div);
return div;
};
var createSingleLoginLayer2 = getSingle(createLoginLayer2);
document.getElementById('addBtn2').onclick = function() {
var loginLayer = createSingleLoginLayer2();
loginLayer.style.display = 'block';
};
</script>
</body>
</html>