You also said you take care to always use ‘===’ in most cases. ‘===’ is hardly the de facto standard equality comparison operator. Just by the fact that you have to consciously make a decision to use the triple equals to “avoid problems like [this]” indicates an inherent problem with the ‘==’ implementation. Simply put, it doesn’t do what you want nor expect. I call that a bug.

The conversion of types functionality is not particularly useful in so far as comparing objects or functions to primitive types and strings. The only use for type conversion is in comparing a number to a string that contains a number: 6.2 == “6.2″ Therefore, I consider this a bug. Most, if not all other scripting languages, convert between primitives but do type checking for objects.

Further supporting this as a bug is that no other language (to my knowledge… please correct me if I am wrong and I very well could be since I have not used every scripting language ;-)) behaves this way except for ECMA script.

To suggest that this is common knowledge is definitely incorrect since every major javascript library currently implements indexOf using ‘==’ instead of ‘===’ which is incorrect.

I am glad that you use ‘===’ and that you are aware of the pitfalls of ‘==’. However, I would venture to guess that 90% of developers out there do not know this and do not have any idea that the libraries they are using implement indexOf incorrectly.