How to discover JS errors in production code in 5 min

Today I was pulled into a customer call where some customer complained that browser froze for him and the UI kept showing Processing.... . Now as usual I was asked to hunt if it was a server issue or did this customer had any errors. I checked from new relic and from haproxy logs but didnt found any. Then it occured to me what if its a JS error, there was no way to find it out. Then I remembered that New relic had a Beta product to detect JS errors. I went an enabled it from Browser->AppName->settings and within 10 min the errors started flowing.

Good news is that there arent that many errors but in entire day there were almost 150 of them. But for a java guy this is good info and now I can hunt the UI team to fix them.

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