如何使用简单的 Javascript 获取文件的上传大小?

How can I get a file#39;s upload size using simple Javascript?(如何使用简单的 Javascript 获取文件的上传大小?)

问题描述

我在其中一个页面上有上传文件功能.我使用 JavaScript 检查文件的扩展名.现在我想限制用户上传大于 1 MB 的文件.有什么方法可以使用 JavaScript 检查文件上传大小.

I have upload file functionality on one of the page. I check for the extension of the file using JavaScript. Now i want to restrict the user from uploading file greater than 1 MB. Is there any way i can check the file upload size using JavaScript.

我的代码目前如下所示:

My code currently look like this:

<script language="JavaScript">
function validate() {
   var filename = document.getElementById("txtChooseFile").value;
   var ext = getExt(filename);
   if(ext == "txt" || ext == "csv")
      return true;
   alert("Please upload Text files only.");
   return false;
}

function getExt(filename) {
   var dot_pos = filename.lastIndexOf(".");
   if(dot_pos == -1)
      return "";
   return filename.substr(dot_pos+1).toLowerCase();
}
</script>

推荐答案

获取文件名的其他方法是您无法在 javascript 中找到有关文件的任何其他详细信息，包括其大小.

Other that aquiring the filename there is no way for you to find out any other details about the file in javascript including its size.

相反，您应该配置服务器端脚本来阻止超大上传.

Instead you should configure server-side script to block an oversized upload.

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