Javascript 兼容IE 预览本地上传图片方法-优快云博客

本文链接：https://blog.youkuaiyun.com/gao497278979/article/details/47400267

该博客介绍了一种在JavaScript中实现本地图片预览的方法，特别针对IE浏览器进行了兼容处理。通过FileReader API和IE的DXImageTransform滤镜来读取和显示选择的图片文件。

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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;

        }
    }
})();