JS to select all checkboxes in Salesforce on the profile level FLS page

selectAll_sfdc.js

var jq = document.createElement('script');
jq.src = "https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js";
document.getElementsByTagName('head')[0].appendChild(jq);

setTimeout(function(){
  var jQ = jQuery.noConflict();
  jQ('input[type="checkbox"][title="Read Access"]').each(function(index,cb){jQ(cb).prop( "checked", true );});
  jQ('[type="submit"][title="Save"]').click();
  
},3000);