如何将数据从文本文件加载到javascript中的变量中

Question

I'm just trying to do something that simple. All I want to do is load the contents of a text file into a variable. The text file is only one line and is always a string. I know there are other threads asking the same question, but as of now, the closest answer I have gotten is this:

var client = new XMLHttpRequest();
client.open('GET', '/foo.txt');
client.onreadystatechange = function() {
   alert(client.responseText);
}
client.send();

The problem with this is that I am trying to load the information into a variable. Not send it as an alert. I have tried this:

var string;
var client = new XMLHttpRequest();
client.open('GET', '/foo.txt');
client.onreadystatechange = function() {
   string = client.responseText;
}
client.send();

This does not work either.

This is not a duplicate of this post , as that post is focused on Ajax, and doesn't actually answer how to import the information. I'm not utilizing Ajax. I want the information from the file to be usable elsewhere in the program.

Answer 1

it is evident that you are trying to make an HTTP request to the user's local computer and for obvious reasons - browsers do not allow this! else hackers would be able to read the entire content of a users C drive if they wanted - or worse!

So - you are required to upload the file! ie <input type="file" id="uploadFile" /> Check this JSFiddle , you would use the onChange event of the input to read the file

For a similar situation, I used file upload to the server and used PHP/c# (cant remember off the top of my head) which returned the required data - this made things a bit easier actually - the server would receive the file and validate, extract required information and return just the required data - although it seems like more work on the server side - which it is a little bit more you can plan it to make reduce the amount of javascript code you might have to write.