You can input a letter in a number input (e), however the interesting part is how Chromium defines the input’s value IDL attribute. Chromium evaluates the user-inputted string to either a floating point number or an empty string, which can cause state problems when the user inputs an incomplete number with an exponent (2e).

This leads to many developers believing there’s a bug in the framework/browser they’re using, when in reality it’s the result of a less-than-ideal HTML spec.

https://github.com/facebook/react/issues/10738 https://github.com/facebook/react/issues/6556 https://bugs.chromium.org/p/chromium/issues/detail?id=379122