Impossible to define static 'length' function on class

[plantain-00]

Fixes #442

[yuit]

I would consider this as grammar check -> like call it checkGrammarStaticPropertyName

[mhegazy]

We should do this in a more generic fashion and not hard code the names. we should use the Function type and make sure we are not redefining any of the properties there. possibly readonly ones only. this way users can add/remove some of these checks.

[plantain-00]

@mhegazy and @yuit , thanks for the review, I will find time to fix these.

I'm wondering how to use the Function type, name === nameof Function.length is not allowed yet, and Function[name] !== undefined will not work for the case of name === "apply".

[yuit]

Thank you for the PR @plantain-00 !

Additional comment is that I believe there need to be distinction between static property and static method declaration when users target ES5, ES6

• ES5 : all (length, name, arguments, caller) should be disallowed for both static property and static method declaration
• ES6: all (length, name, arguments, caller) should be disallowed when declared as static property but (length, arguments, caller, name) should be allow in method declaration ("name" get special treatment definiltely should be allowed here). From trying out in node, when user defined static method declaration with those names they seems override the reserved property except "name". I can't find others in the spec :( @bterlson, could you help confirming whether in ES6(length, arguments, caller) are allowed as static method declaration

EDIT: i make an inline edit, as my original comment is incorrect

[yuit]

Regardless of the previous comment, @vladima points out that this rule should be extended to "ComputedProperty" with string literal of the value: length, name, arguments, caller

Could you add additional tests for such case?

[plantain-00]

@yuit extended to computed property means errors in below code?

class C {
    static caller = { // error: caller
        [name]: "abc", // error: name
        [length]: 1, // error: length
    };
}

[yuit]

@plantain-00 almost but using string literal instead. In your example, it is an expression

class C {
    static caller = { // error: caller
        ["name"]: "abc", // error: name
        ["length"]: 1, // error: length
    };
}

[plantain-00]

any comments?

[bterlson]

@yuit sorry I missed my ping. Confirming that this change is correct, length, arguments, caller, and name are all valid static method names in ES6.

[mhegazy]

why is this an error?

[plantain-00]

There is a comment(above) from yuit:

this rule should be extended to "ComputedProperty" with string literal of the value: length, name, arguments, caller

[plantain-00]

any comments?

[mhegazy]

Fixed by #12065