ipleak.net relies on using a specific js draft spec that is breaking with previous (and established) ECMAscript standards.
The problem is that trailing commas in argument lists and arrow function arguments are not allowed in standard specification JS. Only the non-finalized draft spec for ES2017 allows trailing commas.
Browsers which adhere to finalized standards will therefore have a lot of page elements missing on ipleak.net due to the following errors:
SyntaxError: expected expression, got ')' index.js:129:12 ReferenceError: IpLeak is not defined ipleak.net:38:0
Please remove trailing commas. Not only is it nonstandard, it's also very sloppy.