How &%$&# Mad Are Your Users?
Grumble.js is a library that can be used to determine when users are upset. It does this by listening for when they grumble (for example, shout swear words). It's probably best suited to test environments (particularly when those engaged in the test don't know it's present) but its potential application is far reaching.
Using the experimental SpeechRecognition API that is currently available in the latest version of Google's Chrome browser, developers will be able to log "grumbles" so they can get a "grumbles per minute" metric, or potentially open a help dialog when a user does "grumble." Grumble.js seems to work best according to the developer when the trigger words are included in a sentence, as in "What a stupid #$@! place to but a call to action button!"