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console 命令行工具 X clear

                    
>
console
var button = document.getElementById('btn');
button.addEventListener('click', function(e) {
    if (e.target.tagName == 'BUTTON') {
        document.getElementById('imgModal').style.display = 'block';
    }
})
<button id="btn">点击展开弹窗</button>
<div id="imgModal" class="modal-bg">
    <div class="modal">
        <div class="modal-body">
            <div class="modal-title clearfix">
                <h3 class="fl">上传图片</h3>
                <span class="fr close">+</span>
            </div>
            <div class="modal-content clearfix">
                <ul id="js-list" class="clearfix">
                    <li id="js-add"></li>
                </ul>
            </div>
            <div class="modal-footer clearfix">
                <input type="button" class="btn btn-primary" value="上传" />
                <input type="button" class="btn btn-default" value="取消" />
            </div>
        </div>
    </div>
</div>
        * {
            margin: 0;
            padding: 0;
        }
        #btn {
            margin: 50px;
        }
        .clearfix {
            zoom: 1;
        }
        .clearfix::after {
            display: block;
            overflow: hidden;
            content: "";
            height: 0;
        }
        .fl {
            float: left;
        }
        .fr {
            float: right;
        }
        .modal-bg {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: #eee;
            opacity: 0.7;
        }
        .modal {
            position: relative;
            width: 100%;
            height: 100%;
        }
        .modal-body {
            position: absolute;
            width: 668px;
            height: 608px;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            border: 1px solid #ccc;
            border-radius: 5px;
            background: #fff;
        }
        .modal-title {
            padding: 15px 20px;
            height: 20px;
            line-height: 20px;
            border-bottom: 1px solid #ccc;
        }
        .modal-title h3 {
            display: inline-block;
            text-align: center;
            width: 80px;
            height: 35px;
            font-size: 1em;
            color: red;
            border-bottom: 1px solid red;
        }
        .modal-title .close {
            font-size: 20px;
            font-weight: bold;
            color: #333;
            transform: rotate(45deg);
        }
        ul {
            list-style: none;
        }
        li {
            display: inline-block;
            width: 110px;
            height: 110px;
            margin: 20px;
            background: url("https://p1.pstatp.com/large/3ecd0004b6bdeff4c48d") no-repeat center;
            border: 1px solid #ccc;
            cursor: pointer;
        }
        .modal-content {
            min-height: 476px;
        }
        .modal-footer {
            height: 50px;
            padding: 15px 50px;
            border-top: 1px solid #ccc;
            text-align: center;
        }
        .modal-footer:first-child {
            margin-right: 15px;
        }
        .btn {
            display: inline-block;
            height: 36px;
            padding: 5px 30px;
            background: #fff;
            color: #333;
            border: 1px solid #ccc;
            border-radius: 2px;
            cursor: pointer;
        }
        .btn-primary {
            background: red;
            color: #fff;
            margin-right: 15px;
        }
        .btn-default {
            background: #ccc;
            color: #333;
        }