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Comment by kokanee | Hacker News Reader

One of the biggest warts is the difference between the == and === operators. Eich attempted to alter the behavior of == in order to fix it, but was not allowed to ship the change for fear of backwards incompatibility, forcing him to add a new operator instead. To this day, recommended linter settings disallow use of the == operator entirely.

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`==` and `!=` are still quite handy when you don't want to deal with the distinction between `null` and `undefined`, which is almost always what you want.

If you do this, you need to think through all the possible types for the comparators and how type coercion will affect the expression. For example, `0 == ''`, `[] == ''`, and `[] != []` are all `true`. If you're using typescript to get guarantees about the input types, maybe that's a good use case for using type coercion intentionally.

I find that I really appreciate the explicit rather than the implicit comparisons (requiring `===` in js), especially picking up a new program or coming back to one after some time away. I view it like a database - do I really want multiple ways to show a value is empty? For something like a Boolean you have: `false`, `true` and `null` as valid values (trilean?) that now have to be handled.

Could "use strict;" have silently changed all occurrences of "==" to "==="?

That might introduce silent bugs, a much more reasonable way would be for "use strict"; to throw an error when == is used.

By definition, no. Use strict was a subset of JS.

Ah, I see. So they could have at least excluded "==".

Actually, I was surprised to learn last week that the `eqeqeq` rule that disallows `==` is not in ESLint's recommended set: https://eslint.org/docs/latest/rules/

(And I immediately enabled it for our codebase. Generally I like to just rely on the recommended non-stylistic rules, but this is such an easy footgun that everybody on my team already defaulted to adhering to, that I made an exception.)

Interesting, I could have sworn it was at some point, but maybe I'm thinking of the AirBnB settings.

Yeah I had the same! Someone pointed out the error in a code review, and I was like - why didn't ESLint catch this?

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