javscript上传图片前预览的方法setPreViewImage()

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 <head>
 <meta charset="UTF-8">
 <meta name="Generator" content="EditPlus?">
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 <title>Document</title>
 </head>
 <body>
 <script> 
function setImagePreview() { 
    var docObj = document.getElementById("doc"); 
    var imgObjPreview = document.getElementById("preview"); 
    if (docObj.files && docObj.files[0]) { 
    /*火狐下,直接设img属性*/
imgObjPreview.style.display = 'block'; 
    imgObjPreview.style.width = '150px'; 
    imgObjPreview.style.height = '120px'; 
    /*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 = "150px"; 
    localImagId.style.height = "120px"; 
    /*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; 
} 
</script> 
<input type=file name="doc" id="doc" onchange="javascript:setImagePreview();"> 
<p> 
<div id="localImag">
<img id="preview" width=-1 height=-1 style="diplay: none" />
</div> 
</p>  
 </body>
</html>
原文地址:https://www.cnblogs.com/laijie/p/4745808.html