[Q] String#{trimStart, trimEnd} and String#{trimLeft, trimRigth} equality

[zloirock]

Is it the same functions? If the same - which names they should have?

String.prototype.trimStart === String.prototype.trimLeft; // ???
String.prototype.trimStart.name; // ???
String.prototype.trimLeft.name; // ???

[ljharb]

That's a good question. The options are either:

• they are !==
• they are === and their names are trimStart/trimEnd
• they are === and their names are trimLeft/trimRight

I think that the easiest as well as the one that ends up with the preferred names is the first option - where they are different functions but both call the same internal abstract operation.

[zloirock]

The first way the easiest, but currently in the spec if functions do the same - it's the same functions. Simple example - Set#{keys, values, @@iterator}.

[ljharb]

That's a good point. Based on that pattern, it'd be one of the second two - probably the third option for easier legacy compat.

[zloirock]

Agree.

@sebmarkbage ?

[claudepache]

FWIW, Date.prototype.toGMTString === Date.prototype.toUTCString is true (with name "toUTCString") in Firefox and ES2015, but false in Chrome, Safari (with names "toGMTString" and "toUTCString") and IE (without name).

If we seek spec consistency with that precedent, the option "=== w/ names trimStart/trimEnd" should be picked. Also, I don’t think there is much compat issue around the name of these functions, since functions in IE11 have no name.

Anyway, personally I don’t care, as long as the "official" function (trimStart) gets the "correct" name ("trimStart").

[ljharb]

The current spec makes trimStart and trimEnd be the canonical functions with the appropriate name, which are === to trimLeft/trimRight.

[evilpie]

I think we can close this for now. If this for some reason is causing concern at the meeting we can reopen the issue.