JS上传图片本地实时预览缩略图

时间：2022-12-22 05:38:15
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="width: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;

}

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