一、简单的图片上传并预览功能input[file]

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no" />
    <title>简单的上传图片并预览</title>
    <script type="text/javascript" src="http://code.jquery.com/jquery-1.4.1.min.js"></script>
    <style>
        *{
            padding: 0;
            margin: 0 auto;
        }
        .yg_content{
            margin-top: 50px;
            text-align: center;
        }
        #upimg{
            display: none;
        }
        .yg_content p{
            padding: 10px;
            display: inline-block;
            color: #fff;
            background: #08c;
            border: 1px #ccc solid;
            border-radius: 10px;
        }
        .yg_content p:active{
            opacity: .5;
        }
        .showimg{
            margin: 20px auto;
            border: 1px #ccc solid;
            border-radius: 10px;
            width: 200px;
            height: 200px;
        }
        .showimg img{
            width: 100%;
            height: 100%;
        }
    </style>
</head>
<body>
    <div class="yg_content">
        <input type="file" id="upimg" accept="image/*" onchange="upLoad()">
        <label for="upimg">
            <p>点击上传图片</p>
        </label>
        <div class="showimg">
            <img id="img" src="images/tx_1.jpg" alt="">
        </div>
    </div>
</body>
<script>
    function upLoad(){
        var fileInput = document.getElementById("upimg");
        var file = fileInput.files[0];
        //创建读取文件的对象
        var reader = new FileReader();         
        //创建文件读取相关的变量
        var imgFile;         
        //为文件读取成功设置事件
        reader.onload=function(e) {
            // alert('文件读取完成');
            imgFile = e.target.result;
            console.log(imgFile);
            $("#img").attr('src',imgFile);
        };
 
        //正式读取文件
        reader.readAsDataURL(file);
    }
</script>
</html>