How to catch error in javascript?

Question

I'm trying to catch the error 404 of images that doesn't load on pinging a website.

I want to print 'online' or 'offline' for the pings.

Expected ouput:
online
online
offline

Result:
online
online

My code: https://code.sololearn.com/WA20a816a4a1

Answer 1

Add onerror handler

img.onerror = function()
{
element.innerHTML = "offline";
}

Reference:
https://www.w3schools.com/jsref/event_onerror.asp