Determining that == instead of === is safe for number operators

[Qantas94Heavy]

Let's say that we have the following code:

num % 1 === 0

Now assuming UglifyJS doesn't eliminate this code as side-effect free, it will return the following code:

num%1===0

Now the % operator is defined to return a number (even if it's NaN), so no type conversion is taking place. If we were minifying this manually, we could change === to ==:

num%1==0

which would be no different. Note UglifyJS is able to do this with stuff like booleans:

alert(!troll === false);

is converted to:

alert(!troll==!1);

Can this be done for number operators too?

[curiousdannii]

Note that ==! is still the strict inequality operator. If it was doing what you were suggesting it would be =!.

[Qantas94Heavy]

!== is the strict inequality operator, not ==!. 😉 This is actually the abstract equality operator applied to !troll and !1 (shorthand for false).

[rvanvelzen]

It would probably be best to first implement some form of type inferencing. Otherwise it will only get messier.

[curiousdannii]

Oops yes, how did I get that wrong? :/

[alexlamsl]

Implementing is_number() in the same style as is_boolean() and is_string() would help to enable this optimisation.