39.运用排他思想写面向对象Tab选项卡

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  • 什么是排它思想?清除其它非选中元素的样式, 只设置当前选中元素样式

html

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<div id="tab">
    <ul id="tab_top">
        <li class="tab-item selected">新闻</li>
        <li class="tab-item">视频</li>
        <li class="tab-item">音乐</li>
        <li class="tab-item">军事</li>
        <li class="tab-item">财经</li>
    </ul>
    <div id="tab_bottom">
        <div class="tab-content">新闻的内容</div>
        <div class="tab-content">视频的内容</div>
        <div class="tab-content">音乐的内容</div>
        <div class="tab-content">军事的内容</div>
        <div class="tab-content">财经的内容</div>
    </div>
</div>

css

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<style>
        *{
            margin: 0;
            padding: 0;
        }
        #tab{
            width: 400px;
            height: 300px;
            border: 1px solid #000;
            margin: 100px auto;
        }
        #tab_top{
            list-style: none;
            width: 100%;
            height: 50px;
            line-height: 50px;
            text-align: center;
            display: flex;
            justify-content: space-between;
        }
        #tab_top>li{
            width: 80px;
            height: 100%;
            background: skyblue;
            border-right: 1px solid #ccc;
        }
        #tab_top>li:last-child{
            border-right: none;
        }
        #tab_bottom{
            width: 100%;
            height: 250px;
        }
        #tab_bottom>.tab-content{
            width: 100%;
            height: 100%;
            display: none;
        }
        .selected{
            background: red !important;
        }
    </style>

js

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<script>
    class Tab{
        constructor(){
            this.oTabItems = document.querySelectorAll(".tab-item");
            this.oTabContents = document.querySelectorAll(".tab-content");
            this.oTabContents[0].style.display = "block";
            this.previousIndex = 0;
        }
        addClickEvent(){
            for(let i = 0; i < this.oTabItems.length; i++){
                let tabItem = this.oTabItems[i];
                tabItem.onclick = () => {
                    this._change(i);
                }
            }
        }
        addMoveEvent(){
            for(let i = 0; i < this.oTabItems.length; i++){
                let tabItem = this.oTabItems[i];
                tabItem.onmousemove = () => {
                    this._change(i);
                }
            }
        }
        /*如果在方法名称前面加上_, 代表告诉其他的程序员这个是一个私有的方法, 不要调用
        * 注意点: 仅仅是告诉别人这个是一个私有的方法, 并不是真正的是一个私有的方法*/
        _change(i){
            // 1.排它
            let preTabItem = this.oTabItems[this.previousIndex];
            preTabItem.className = preTabItem.className.replace("selected", "");
            let preTabContent = this.oTabContents[this.previousIndex];
            preTabContent.style.display = "none";

            // 2.设置当前的样式
            let curTabItem = this.oTabItems[i];
            curTabItem.className = curTabItem.className + " selected";
            let curTabContent = this.oTabContents[i];
            curTabContent.style.display = "block";

            // 3.保存当前的索引
            this.previousIndex = i;
        }
    }
    let tab = new Tab();
    tab.addClickEvent();
    // tab.addMoveEvent();
</script>

Tab效果