Using Boolean constructor for type casting about mapsapi-codestyle HOT 8 CLOSED

• We use simple rule for all conversions
• Don't use new with Boolean

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We use simple rule for all conversions

That's senseless. Your rule leeds to errors.

Don't use new with Boolean

I never do that. But imagine that your code is API, and third-party developers pass values to it. And - surprise! - they have style guide of their own.

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and third-party developers pass values to it

All our code based on contract between developer and third-party developer. If third-party developer violates contract this is his fault.

In your example Boolean and !! have same result:

> var b = new Boolean(false);
undefined
> b
false
> Boolean(b)
true
> !!b
true

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Okay, new Boolean(false) was a bad example. Take any other ‘truthy’ value, like [].
Please, explain the logic to me: you allow third-party to provide values of any type instead of Boolean, but your internal cast is not the same as browser default. How should third-party know that?

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We use type conversion only when we want to explicitly convert a value to the boolean type (or a string or a number for that matter). In other words, only when we going to encapsulate some logic behind obtaining the value in question. For example:

SomeClassWithArrayWithin.prototype.isEmpty = function () {
    return Boolean(this._array.length);
};

Here we deliberately lose information about the array within the implementation and, of course, about its length.

In other cases we just rely upon type coercion.

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Take any other ‘truthy’ value, like [].
Please, explain the logic to me: you allow third-party to provide values of any type instead of Boolean, but your internal cast is not the same as browser default.

I don't understand problem with Boolean:

> var a = []
undefined
> Boolean(a)
true
> !!a
true

but your internal cast is not the same as browser default

What do you mean? Provide examples please.

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We use type conversion only when we want to explicitly convert a value to the boolean type (or a string or a number for that matter)

Does it mean that you are using expressions like that?

if (Boolean(arr.length) === false) {
    // ...
}

And what are you doing with polymorphic functions?

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Issue is closed, in Harmony this issue resolved.
http://people.mozilla.org/~jorendorff/es6-draft.html#sec-toboolean

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