input file 控件选择图片预览

<script>
    function getObjectURL(file) {
        var url = null;
        if (window.createObjectURL != undefined) { // basic
            url = window.createObjectURL(file);
        } else if (window.URL != undefined) { // mozilla(firefox)
            url = window.URL.createObjectURL(file);
        } else if (window.webkitURL != undefined) { // webkit or chrome
            url = window.webkitURL.createObjectURL(file);
        }
        return url;
    }
    function previewimg(file, imgTag) {
        var objUrl = getObjectURL(document.getElementById(file).files[0]);
        if (objUrl) {
            document.getElementById(imgTag).src = objUrl;
        }
    }
</script>

使用

<img id="myimg1" src="" style="height:90px;" />
<input id="uploadimg1" type="file" name="img1" value="" onchange="previewimg('uploadimg1', 'myimg1');" />