isBoolean?

[ghost]

Would isBoolean() be a good validator?

Some fields only accepts true or false (checkboxes).

[chriso]

True, but you can assign a custom value to checkbox for when it's checked.

I've always provided the following filters:

toBoolean()                     //True unless str = '0', 'false', or str.length == 0
toBooleanStrict()               //False unless str = '1' or 'true'

[awvalenti]

A question: why does toBoolean() accept stuff other than 'true' and 'false' and why so does toBooleanStrict()?

[chriso]

It mimics the way JavaScript coerces strings to a boolean

[awvalenti]

You said JavaScript coerces strings to boolean. By which means?

I checked the construct

Boolean(myString)

and

if (myString)

, but unfortunately they evaluate the string 'false' to true... Really odd! The second case is understandable, but the first is definetely not.

[chriso]

The Boolean constructor obviously has different semantics. I mean the way non-empty strings are considered truth-y:

console.log("123" ? true : false); //true
//or just
console.log(!!"123"); //true

I designed toBoolean() to do the same except in the case of "0" or "false" which will often be passed as request parameters.

[awvalenti]

I'm still unable to see the mimics there. If I got it right:

JavaScript:
str.length == 0 ? false : true

toBoolean():
str.length == 0 || str == 'false' || str == '0' ? false : true

toBooleanStrict():
str == '1' || str == 'true' ? true : false

[chriso]

Correct. "1" or "true" is considered true, "0" or "false" is considered false, and then your choice of toBoolean() or toBooleanStrict() controls how other strings are coerced.

[sebpiq]

What about if I'm doing server-side validation (I mean that the data hasn't been submitted through a form, therefore no checkbox), and I actually require the value to be a boolean ?

[chriso]

@sebpiq it's a string validation/sanitization library. Checking for a boolean primitive is simple however, e.g. to check for true only => value && typeof(value) === 'boolean'

[sebpiq]

Oh right ... sorry, I guess I was mixed up by the isArray, isNumber and so on ... I was actually looking for an all-purpose validation library, but I guess I've found what I needed now.