使用 XMLHttpRequest 获取服务器中的文件存在

Question

I have this code to check if there is a file with the given URL in the server or not. it returns true if there is a file and false if else...

The issue is if there is not a file, in the chrome's console I can see a 404 error which I expect because the given URL doesn't exist But:

• I wonder if this error will affect the execution of the whole code and the code quality?!

• How to remove the error if there is any solution?

 // Check if file exist in the server function fileExist(url) { return new Promise((resolve) => { const xhr = new XMLHttpRequest(); xhr.open('HEAD', url, true); xhr.onload = function () { return resolve(xhr.status==200) }; xhr.onerror = function () { return resolve(xhr.status==200) }; xhr.send(); }); }

Answer 1

The only problem I can see is that your function treats any error as the file not existing. You should check specifically for xhr.status == 404 in the onerror function. Anything else could be a server failure, network error, etc. and should trigger an error handler.

A better way to do this would be to have a server script that checks whether the file is there. Make an AJAX request to that script, and it can return a simple true/false response. But this also has more overhead.