检查本地 HTML 文件是否存在并加载

Question

I'm new to JavaScript. I'm trying to check if an HTML file exists on my local machine.

• If exists → Load the HTML file and display it in browser.
• If not exists → Load and display a PNG file in browser.

Couldn't find documentation for this problem online.

Answer 1

You can use an XMLHttpRequest

function LinkCheck(url)
{
    var http = new XMLHttpRequest();
    http.open('HEAD', url, false);
    http.send();
    return http.status != 404;
}

Answer 2

U can use the fetch api and to mimic http request for local text files:

(async () => {
  const response = await fetch('index.html');
  console.log(response.body);
})();

Other solution is to use FileReader class

Check this out: https://www.javascripture.com/FileReader