Javascript：使用 AJAX 读取文本文件
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Javascript: Read Text File using AJAX
提问by Fares K. A.
Can't get AJAX to work! I have a marquee on a website, got it working! But I want it to find the text of the marquee in a text file, and I want it to read the text in the text file (which is one line) and assign it to the variable called content, which is a global variable in the script tag.
无法让 AJAX 工作！我在一个网站上有一个选框，让它工作了！但我希望它在文本文件中找到选取框的文本，并且我希望它读取文本文件中的文本（这是一行）并将其分配给名为 的变量content，该变量是脚本中的全局变量标签。
When I run the website (local IIS), the marquee text is: "undefined" (without the quotes).
当我运行网站（本地 IIS）时，选取框文本是：“未定义”（不带引号）。
Why isn't it assigning the text to the variable content?
为什么不将文本分配给变量content？
var content
function loadXMLDoc()
{
var textfile;
if (window.XMLHttpRequest)
{
textfile = new XMLHttpRequest();
}
textfile.onreadystatechange = function ()
{
if (textfile.readyState == 4 && textfile.status == 200)
{
content = textfile.responseText;
}
}
textfile.open("GET", "C:\Users\Fares\Dropbox\Sync\College\Computing\DeltaOne\MarqueeText.txt", true);
textfile.send();
}
EDIT:A million thanks to @kuncajs, as he pointed out I forgot to call the function! :) Fixed! Thanks to everyone else!
编辑：一百万感谢@kuncajs，正如他指出的那样，我忘记调用该函数！：） 固定的！感谢其他所有人！
采纳答案by kuncajs
Do not use local paths like:
C:\Users\Fares\Dropbox\Sync\College\Computing\DeltaOne\MarqueeText.txt
不要使用本地路径，例如：
C:\Users\Fares\Dropbox\Sync\College\Computing\DeltaOne\MarqueeText.txt
Place it in the www directory of your IIS and state the path like:
localhost/text.txt
把它放在你的 IIS 的 www 目录中，并声明如下路径：
localhost/text.txt
The server can have restricted access to your filesystem and also you should try relative paths like text.txtor absolute paths /text.txtso the paths work even when you deploy it in the production environment.
服务器可以限制访问您的文件系统，并且您应该尝试使用相对路径text.txt或绝对路径，/text.txt这样即使您将其部署在生产环境中，这些路径也能正常工作。
EDIT:So if this did not help then make sure that you really call the loadXMLDoc()function. Also check that everything you do is afterthe AJAX ends! I mean you do the assignment in the if - when AJAX is done but you should also initialize your marquee !AFTER! the text is loaded. If you do it before it will be undefined
编辑：因此，如果这没有帮助，请确保您确实调用了该loadXMLDoc()函数。另外，请检查你做的一切都是经过了AJAX结束！我的意思是你在 if 中进行分配 - 当 AJAX 完成但你也应该初始化你的选取框！AFTER！文本已加载。如果你之前这样做，它将是未定义的
回答by TheC4keIsASpy
Try using a relative or absolute path first.
首先尝试使用相对或绝对路径。
If that doesn't work check that when using your browser you can access the file (let's say your website is on mysite.com/index.html, try opening mysite.com/text.txt)
如果这不起作用，请检查在使用浏览器时是否可以访问该文件（假设您的网站已打开mysite.com/index.html，请尝试打开mysite.com/text.txt）
If you can't access it using your browser then you will have to configure your server to allow this file to be read, never tried IIS so I can't help you there.
如果您无法使用浏览器访问它，那么您必须配置您的服务器以允许读取此文件，从未尝试过 IIS 所以我无法帮助您。
Also since you are asking your XHR to be asynchronous it might take a little time before the variable is populated (depending on your/your server's speed)
此外，由于您要求 XHR 是异步的，因此在填充变量之前可能需要一些时间（取决于您/您的服务器的速度）
