Editing 直接预览本地图片，支持 IE8

<!DOCTYPE html>
<html>

<head>
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <meta charset="utf-8" />
  <meta name="referrer" content="never">

  <title>直接预览本地图片，支持 IE8</title>
</head>

<body>

  <h2>JavaScript 直接预览本地图片，支持 IE8</h2>
  <input type="file" id="fileInput" />
  <div id="previewContainer"
    style="filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);width:64px; height:64px;margin-top:10px;">
    <img id="previewImage" src="/favicon.ico" style="width:100%; height:100%;" />
  </div>

</body>

</html>

function preImg(fileInput, containerId, imageId) {
    var allowedExts = [".jpg", ".jpeg", ".gif", ".png", ".bmp"];
    var fileExt = fileInput.value.substring(fileInput.value.lastIndexOf('.'), fileInput.value.length).toLowerCase();

    if (allowedExts.indexOf(fileExt) == -1) {
        fileInput.value = "";
        alert("只能上传 jpg gif png bmp 格式图片");
    } else {
        var container = document.getElementById(containerId);
        var image = document.getElementById(imageId);

        if (container.filters) {
            image.style.display = "none";
            fileInput.select();
            container.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = document.selection.createRange().text;
        } else {
            image.src = window.URL.createObjectURL(fileInput.files.item(0));
        }
    }
}

var fileInput = document.getElementById('fileInput');
fileInput.onchange = function () {
    preImg(fileInput, 'previewContainer', 'previewImage');
}