Check if Javascript script exists on page

Question

I have a bookmarklet that I\'ve made and it loads a script from my server onto the users current page. However I have an if check in my script that if a condition is not met the

Answer 1

Solution with ES6, no jQuery:

const url = 'http://xxx.co.uk/xxx/script.js';

function scriptExists(url) {
  return document.querySelectorAll(`script[src="${url}"]`).length > 0;
}

if(scriptExists(url){
  ...
}

It's not recommended to inline JS into HTML. Instead add event listeners:

 function bookmark() {
   if(scriptExists(url){
     ...
   }
 }

 document.querySelectorAll('a.bookmark').addEventListener('click', 
 bookmark, false);