Fix this reference for functions

[nwalters512]

Description

This PR fixes the bug described in #38720. Functions like content and title weren't being called with the correct this reference.

Motivation & Context

As far as I can tell, #36652 introduced this regression. It switched from calling the function with a specific this value to calling it with that value as the first argument.

While this appears to have been unintentional, folks may have started relying on that first argument as a workaround, and thus it could be considered part of the API. I didn't do anything about that yet, but it might be reasonable to retain both the old and new behavior (that is, for functions like content, call it with both a specific this value and an explicit argument). I can make that change and update the documentation if requested.

I repurposed the existing execute() function to support this. If a second argument is provided, it will be an array, and the first value will be treated as the this argument. This is done by just passing the entire arguments array to call. This required adding undefined as the first value in some places that don't expect an specific this value.

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Related issues

Fixes #38720.

[XhmikosR]

/CC @GeoSot

[GeoSot]

Suggested change

	return execute(arg, [undefined, this])
	return typeof arg === 'function' ? arg.call(this._element) : arg

I suppose it is better to change only this, as it is count as a regression, and add a test, instead of messing all the rest calls

[nwalters512]

This callsite doesn't actually matter, AFAICT. There are two calls where the this argument is important:

• _resolvePossibleFunction in js/src/tooltip.js
• The call to execute(this._config.placement, ...) in _createPopper in js/src/tooltip.js

I can update those two call sites to use the typeof arg === 'function' ... pattern if you'd prefer that I avoid changing execute?

[nwalters512]

@mdo @GeoSot 👋 anything I can do to help this along?

[mdo]

Seems good to go @GeoSot?

[nwalters512]

@mdo @GeoSot checking in to see if there's anything else I can do to help get this merged!