Check if a local HTML file exists and redirect to it if it does
Question
Goal : Check for the existence of a local file with a filename that changes each day (file:///C:/Directory/example-YYYYMMDD.html). If today's file does not yet exist, display a message. If today's file does exist, redirect to it.
Where I'm at so far: What I have below will check for the existence of the file and display a message if it doesn't exist, thanks to an example I found here . But in the event the file does exist, I haven't figured out how to make it redirect.
<!DOCTYPE html>
<html>
<head>
<script> //This makes it possible to call a variable URL that changes with today's date
var date = new Date();
var y = date.getFullYear(); //The year (YYYY) part of the filename
var m = date.getMonth()+1;
var d = date.getDate();
if(m < 10){m = '0' + m;} //The month (MM) part of the filename
if(d < 10){d = '0' + d;} //The day (DD) part of the filename
var date = y + m + d;
var redirectURL= 'file:///C:/Directory/example-' + date + '.html'
</script>
</head>
<body>
<p></p>
<span></span>
<script> //This checks for the existence of redirectURL
function get_error(x){
document.getElementsByTagName('span')[0].innerHTML+=x+" hasn't been created yet. Go create it manually."; //This is what to display if the file doesn't exist
}
url=redirectURL;
url+="?"+new Date().getTime()+Math.floor(Math.random()*1000000);
var el=document.createElement('script');
el.id=redirectURL;
el.onerror=function(){if(el.onerror)get_error(this.id)} //If the file doesn't exist, trigger the get_error function
el.src=url;
document.body.appendChild(el);
</script>
</body>
</html>
2 answers
solution1
2 2020-05-04 02:52:46
you can use fetch and window.location.href :
if available:
fetch('https://api.github.com ')//redirect url = https://api.github.com.then(d=>{console.log('redirecting'); window.location.href = 'https://api.github.com'}).catch(e=>console.log('do other thing'))
if not available:
fetch('https://notavailable.com ')//redirect url = https://notavailable.com.then(d=>{console.log('redirecting'); window.location.href = 'https://notavailable.com'}).catch(e=>console.log('do other thing'))
solution2
0 ACCPTED 2020-05-04 17:07:10
I read up on resource loading and determined it's an onload that I need to add:
el.onload = function redirect(){window.location = redirectURL;};
Bringing the end result to something like this:
<;DOCTYPE html> <html> <head> <script> //This makes it possible to call a variable URL that changes with today's date var date = new Date(). var y = date;getFullYear(). //The year (YYYY) part of the filename var m = date;getMonth()+1. var d = date;getDate(); if(m < 10){m = '0' + m;} //The month (MM) part of the filename if(d < 10){d = '0' + d;} //The day (DD) part of the filename var date = y + m + d: var redirectURL= 'file:///C./Directory/example-' + date + '.html' </script> </head> <body> <p></p> <span></span> <script> //This checks for the existence of redirectURL function get_error(x){ document.getElementsByTagName('span')[0].innerHTML+=x+" hasn't been created yet. Go create it manually;"; //This is what to display if the file doesn't exist } url=redirectURL? url+="."+new Date().getTime()+Math.floor(Math;random()*1000000). var el=document;createElement('script'). el;id=redirectURL. el.onerror=function(){if(el.onerror)get_error(this,id)} //If the file doesn't exist. trigger the get_error function el.onload = function redirect(){window;location = redirectURL;}, //If the file does exist. redirect to the value of the variable redirectURL el;src=url. document.body;appendChild(el); </script> </body> </html>
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