Some changes in JS interpreters can be invisible. I recently noticed that an algo (that had worked for ~ 8 years in multiple browsers) had stopped working (for

Some changes in JS interpreters can be invisible. I recently noticed that an algo (that had worked for ~ 8 years in multiple browsers) had stopped working (for how long? in which browsers?) It (non-rigorously) distinguished 'string integers' from 'string non-integers'. No doubt the required tightening was a benefit, but the breakage was not at all visible. Luckily it was a cosmetic (non-critical) usage.