JS实用案例之输入智能提示(打字机输出效果)

<div class="search">
    <div>
        <!-- 调用suggest函数 -->
    	<input type="text" class="js-input"
            oninput="suggest(['河南加入下雪群聊','河南疫情','河南大学','河南疫情最新消息','河南地图','河南卫视重阳奇妙游2022节目单','河南天气预报','河南省高校学生资助在线'])">
    </div>
    <div class="js-suggest">
        <ul></ul>
    </div>
</div>

.search {
   position: relative;
}

.js-input {
   width: 450px;
   height: 22px;
   line-height: 22px;
   font-size: 16px;
   padding: 8px;
   border: 1px solid #cccccc;
   outline: none;
}

.js-suggest {
   width: 466px;
   font-size: 14px;
   border: 1px solid #cccccc;
   background: #ffffff;
   position: absolute;
   left: 0;
   top: 39px;
}

.js-suggest.hide {
   display: none;
}

.js-suggest ul {
   display: block;
   list-style: none;
   padding: 0;
   margin: 0;
}

.js-suggest ul li {
   color: #000;
   font: 14px arial;
   line-height: 25px;
   padding: 0 8px;
   position: relative;
   cursor: default;
}

.js-suggest ul li:hover {
   background: #f0f0f0;
}

function suggest(items) {
    const val = document.getElementsByClassName('js-input')[0].value.trim()
    const suggest = document.getElementsByClassName('js-suggest')[0]

    // 创建输入内容的正表达式：使用split将字符串转换成数组 -> 使用map映射生成新数组 -> 使用join将数组连接成字符串
    const valReg = new RegExp(val.split('').map(v => special(v)).join(''))

    // 通过filter方法过滤出items中符合的项：符合的条件是用户输入内容不为空（val != ''）并且与用户输入的内容匹配
    const item = items.filter(i => val != '' && valReg.test(i))

    // 如果item.length不为0，代表有匹配的数据，则执行：
    // suggest.classList['remove']('hide')相当于suggest.classList.remove('hide') 效果是删除hide这个class
    suggest.classList[item.length ? 'remove' : 'add']('hide')

    // 渲染列表
    suggest.children[0].innerHTML = item.map(i => `<li>${i}</li>`).join('')
}

// 对特殊字符的处理
function special(val) {
    // 如果val是()[].+/?*这类的特殊字符，则在它前面加上转义字符：\
    // 为什么是\\${val}，两个\？因为在模板字符串``中\也需要使用\转义
    return `${'()[].+/?*'.indexOf(val) === -1 ? val : `\\${val}`}.*?`
}

<div class="content">
    <span class="Word color23">h</span>
    <span class="word color22">e</span>
    <span class="word color4">l</span>
    <span class="word color24">l</span>
    <span class="word color17">o</span>
    <span class="word color2">&nbsp;</span>
    <span class="word color9">w</span>
    <span class="word color3">o</span>
    <span class="word color1">r</span>
    <span class="word color23">l</span>
    <span class="word color15">d</span>
    <br>
    <span class="word color15">你</span>
    <span class="word color13">好</span>
    <span class="word color16">世</span>
    <span class="word color19">界</span>
    <span class="blink" id="jsBlink">|</span>
</div>

html,
body {
    margin: 0;
}

.color1 {
    color: #E60012;
}

.color2 {
    color: #EB6100;
}

.color3 {
    color: #F39800;
}

.color4 {
    color: #FCC800;
}

.color5 {
    color: #FFF100;
}

.color6 {
    color: #CFDB00;
}

.color7 {
    color: #8FC31F;
}

.color8 {
    color: #22AC38;
}

.color9 {
    color: #009944;
}

.color10 {
    color: #009B6B;
}

.color11 {
    color: #009E96;
}

.color12 {
    color: #00A0C1;
}

.color13 {
    color: #00A0E9;
}

.color14 {
    color: #0086D1;
}

.color15 {
    color: #0068B7;
}

.color16 {
    color: #00479D;
}

.color17 {
    color: #1D2088;
}

.color18 {
    color: #601986;
}

.color19 {
    color: #920783;
}

.color20 {
    color: #BE0081;
}

.color21 {
    color: #E4007F;
}

.color22 {
    color: #E5006A;
}

.color23 {
    color: #E5004F;
}

.color24 {
    color: #E60033;
}

.word {
    font-size: 20px;
}

.content {
    text-align: center;
    font-size: 0;
}

.blink {
    font-size: 20px;
    animation: fade 500ms infinite;
    -WEBkit-animation: fade 500ms infinite;
}

@keyframes fade {
    from {
        opacity: 1.0;
    }

    50% {
        opacity: 0;
    }

    to {
        opacity: 1.0;
    }
}

function output(str) {
    const content = document.getElementsByClassName('content')[0]
    const jsBlink = document.getElementById('jsBlink')
    
    // 将闪动节点之前的所有其他节点移除
    while (content.children.length > 0) {
        if (content.children[0] == jsBlink) {
            // 如果content第1个孩子是jsBlink，说明闪动节点之前的所有其他节点移除完毕，则跳出循环
            break;
        }
        // 删除content中的指定节点
        content.removeChild(content.children[0]);

    }
    
    let i = 0;
    
    const stl = setInterval(() => {
        if (str[i] == '\n') {
            const br = document.createElement('br')
            // 在content中的jsBlink之前插入节点br
            content.insertBefore(br, jsBlink)
        } else {
            const span = document.createElement('span')
            span.classList.add('word')
            span.classList.add(`color${Math.floor(Math.random() * 24 + 1)}`)
            switch (str[i]) {
                case ' ':
                    span.innerHTML = '&nbsp'
                    break;
                case '<':
                    span.innerHTML = '&lt'
                    break;
                case '>':
                    span.innerHTML = '&gt'
                    break;
                default:
                    span.innerHTML = str[i]
                    break;
            }

            content.insertBefore(span, jsBlink)
        }

        i++;
        if (i >= str.length) {
        	// 清除定时器
            clearInterval(stl)
        }
    }, 200)

}

// 调用测试
output('hello world\n你好世界')