单例设计模式
一个class类，new 多次，始终只有一个最终生成的实例，即new class() ===new class() ===new class();
单例设计模式，实现过程为，一个闭包，用一个变量记录是否已经 new实例过，如果是返回记录的实例。否则new一个实例并赋值给闭包变量返回。参考以下弹窗设计
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| <!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
* {
margin: 0;
padding: 0;
}
.mask {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
width: 300px;
height: 200px;
margin: auto;
display: none;
}
.mask .title {
background-color: darkcyan;
color: #fff;
height: 30px;
line-height: 30px;
padding: 0 10px;
box-sizing: border-box;
}
.mask .content {
background-color: #ccc;
color: 0.333;
padding: 20px;
box-sizing: border-box;
height: 140px;
}
.mask .btns {
height: 30px;
background-color: darkgrey;
text-align: right;
line-height: 30px;
padding: 0 10px;
box-sizing: border-box;
}
</style>
</head>
<body>
<button id="btn" onclick="openMask()">打开弹窗</button>
</body>
</html>
<script>
const singeFunction = (function () {
class Mask {
constructor() {
this.el = null;
this.el = document.createElement("div");
this.el.className = "mask";
document.body.appendChild(this.el);
this.bindEvent();
this.onSubmit = null;
this.onCancel = null;
}
create(opt) {
this.onSubmit = opt.submit;
this.onCancel = opt.cancel;
this.el.innerHTML = `
<div class="title">${opt.title || "默认标题"}</div>
<div class="content">${opt.msg || "默认内容"}</div>
<div class="btns">
<button class="save">保存</button>
<button class="cancel">取消</button>
</div>`;
this.el.style.display = "block";
}
bindEvent() {
let that = this;
this.el.addEventListener("click", function (e) {
let tag = e.target;
if (tag.className === "cancel") {
that.el.style.display = "none";
that.onCancel();
} else if (tag.className === "save") {
that.el.style.display = "none";
that.onSubmit();
}
});
}
}
var instance = null;
return function () {
if (instance) {
return instance;
}
instance = new Mask();
return instance;
};
})();
function openMask() {
var fn = singeFunction();
fn.create({
title: "标题" + Math.random(),
content: "内容" + Math.random(),
submit: function () {
alert("你点击了确定");
},
cancel: function () {
alert("你点击了取消");
},
});
}
</script>
|
