Adds documentation about selectors

[mburridge]

Closes #17082

What?

Adds documentation for the following selectors:

• hasFinishedResolution
• hasStartedResolution
• isResolving

to the README file for the @wordpress/data package.

Why?

As per #17082

How?

Doc blocks copied from selectors.js

Testing Instructions

Testing Instructions for Keyboard

Screenshots or screencast

[ndiego]

I think this is good to merge, but in looking at the linked issue, the author is looking for examples of how to use each. So I would add a follow-up issue to add examples to the doc blocks of each selector.

[mburridge]

@ndiego I've added an example. Please review.

@ryanwelcher Please sanity check the code example. Is it too specific? Should it be more generalised?

[ryanwelcher]

There are a few issues with the snippet mentioned below. Additionally, we should also adhere to the JavaScript coding standards when it comes to spacing. I have added some suggestions for spacing but there are also some changes needed for line length etc.

I have take the liberty of formatting the code locally for reference:

import { useSelect } from '@wordpress/data';
import { store as coreDataStore } from '@wordpress/core-data';

function Component() {
	const result = useSelect( ( select ) => {
		const query = { per_page: 20 };
		const selectorArgs = [ 'postType', 'page', query ];

		return {
			pages: select( coreDataStore ).getEntityRecords( ...selectorArgs ),
			hasStartedResolution: select( coreDataStore ).hasStartedResolution(
				'getEntityRecords', // _selectorName_
				selectorArgs
			),
			hasFinishedResolution: select(
				coreDataStore
			).hasFinishedResolution( 'getEntityRecords', selectorArgs ),
			isResolving: select( coreDataStore ).isResolving(
				'getEntityRecords',
				selectorArgs
			),
		};
	} );

	console.log( result.hasStartedResolution );
	console.log( result.hasFinishedResolution );
	console.log( result.isResolving );
	console.log( result.pages );

	return null;
}

[ryanwelcher]

Suggested change

	console.log(result.isResolving);
	console.log(result.isResolving);
	console.log( result.pages );

Adding for completeness.

[mburridge]

I don't think this is necessary as we're talking about the selectors from the @wordpress/data package here.

[ryanwelcher]

LTGM!