JS上传图片本地实时预览缩略图

HTML 代码如下 
<body> <table width="100%" border="0" cellspacing="0" cellpadding="0"> <tbody> <tr> <td height="101" align="center"> <div id="localImag" style="border: 1px solid red;"> <img id="preview" src="" width="100" height="100" style="display: block;border: 1px solid blue;" /> </div> </td> </tr> <tr> <td align="center" style="padding-top:10px;"> <form method="get" action="xznetwork" name="textfile"> <input type="file" name="file" id="doc" multiple="multiple" style="150px;" onchange="javascript:setImagePreview();"> </form> </td> </tr> </tbody> </table> </body>
JavaScript 代码如下


//下面用于图片上传预览功能
function setImagePreview(avalue) {
    //input
    var docObj = document.getElementById("doc");
    //img
    var imgObjPreview = document.getElementById("preview");
    //div
    var divs = document.getElementById("localImag");
        if (docObj.files && docObj.files[0]) {
            //火狐下,直接设img属性
            imgObjPreview.style.display = 'block';
            imgObjPreview.style.width = '100px';
            imgObjPreview.style.height = '100px';
            //imgObjPreview.src = docObj.files[0].getAsDataURL();
            //火狐7以上版本不能用上面的getAsDataURL()方式获取,需要一下方式
            imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);
        } else {
            //IE下,使用滤镜
            docObj.select();
            var imgSrc = document.selection.createRange().text;
            var localImagId = document.getElementById("localImag");
            //必须设置初始大小
            localImagId.style.width = "100px";
            localImagId.style.height = "100px";
            //图片异常的捕捉,防止用户修改后缀来伪造图片
            try {
                localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
                localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
            } catch(e) {
                alert("您上传的图片格式不正确,请重新选择!");
                return false;
            }
            imgObjPreview.style.display = 'none';
            document.selection.empty();
        }
    return true;
}
原文地址:https://www.cnblogs.com/chen-lhx/p/5016526.html