js 上传图片预览

  var loadImageFile = (function () {
                if (window.FileReader) {
                    var oPreviewImg = null, oFReader = new window.FileReader(),
            rFilter = /^(?:image\/bmp|image\/cis\-cod|image\/gif|image\/ief|image\/jpeg|image\/jpeg|image\/jpeg|image\/pipeg|image\/png|image\/svg\+xml|image\/tiff|image\/x\-cmu\-raster|image\/x\-cmx|image\/x\-icon|image\/x\-portable\-anymap|image\/x\-portable\-bitmap|image\/x\-portable\-graymap|image\/x\-portable\-pixmap|image\/x\-rgb|image\/x\-xbitmap|image\/x\-xpixmap|image\/x\-xwindowdump)$/i;

                    oFReader.onload = function (oFREvent) {
                        if (!oPreviewImg) {
                            var newPreview = document.getElementById("imagePreview");
                            oPreviewImg = new Image();
                            oPreviewImg.style.width = (newPreview.offsetWidth).toString() + "px";
                            oPreviewImg.style.height = (newPreview.offsetHeight).toString() + "px";
                            newPreview.appendChild(oPreviewImg);
                        }
                        oPreviewImg.src = oFREvent.target.result;
                    };

                    return function () {
                        var aFiles = document.getElementById("imageInput").files;
                        if (aFiles.length === 0) { return; }
                        if (!rFilter.test(aFiles[0].type)) { alert("You must select a valid image file!"); return; }
                        oFReader.readAsDataURL(aFiles[0]);
                    }

                }
                if (navigator.appName === "Microsoft Internet Explorer") {
                    return function () {
                        document.getElementById("imagePreview").filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = document.getElementById("imageInput").value;

                    }
                }
            })();

 <style>
        #imagePreview
        {
            width: 260px;
            height: 240px;
            float: right;
            filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);
        }
    </style>

<div id="imagePreview"></div>
    <p><input id="imageInput" type="file" name="myPhoto" onchange="loadImageFile();"><br><input type="submit" value="Send" /></p