jquery: Specialize .val() for elements with known value types

[andersk]

If the user explicitly provides a specific element class like $<HTMLInputElement>("input").val(), this lets us infer the result as string | undefined rather than string | number | string[] | undefined.

Please fill in this template.

• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code. (Compile and run.)
• Add or edit tests to reflect the change.
• Follow the advice from the readme.
• Avoid common mistakes.
• Run npm test <package to test>.

Select one of these and delete the others:

If changing an existing definition:

• Provide a URL to documentation or source code which provides context for the suggested changes: https://github.com/jquery/jquery/blob/3.x-stable/src/attributes/val.js
• If this PR brings the type definitions up to date with a new version of the JS library, update the version number in the header.

[typescript-bot]

@andersk Thank you for submitting this PR!

This is a live comment which I will keep updated.

1 package in this PR

• jquery — on npm, on unpkg
  • owner-approval: @johnnyreilly

Code Reviews

Because this is a widely-used package, a DT maintainer will need to review it before it can be merged.

You can test the changes of this PR in the Playground.

Status

• ✅ No merge conflicts
• ✅ Continuous integration tests have passed
• ✅ Most recent commit is approved by a DT maintainer

All of the items on the list are green. To merge, you need to post a comment including the string "Ready to merge" to bring in your changes.

---

Diagnostic Information: What the bot saw about this PR

{
  "type": "info",
  "now": "-",
  "pr_number": 66801,
  "author": "andersk",
  "headCommitOid": "5b98d0468e07c4134fcbbf2f0459f50990ea9e73",
  "mergeBaseOid": "027ee9cdb7d69d3a06d8420341e9231e10bfaa77",
  "lastPushDate": "2023-09-22T20:54:02.000Z",
  "lastActivityDate": "2023-10-04T22:21:47.000Z",
  "mergeOfferDate": "2023-10-04T19:27:12.000Z",
  "mergeRequestDate": "2023-10-04T22:21:47.000Z",
  "mergeRequestUser": "andersk",
  "hasMergeConflict": false,
  "isFirstContribution": false,
  "tooManyFiles": false,
  "hugeChange": false,
  "popularityLevel": "Critical",
  "pkgInfo": [
    {
      "name": "jquery",
      "kind": "edit",
      "files": [
        {
          "path": "types/jquery/JQuery.d.ts",
          "kind": "definition"
        },
        {
          "path": "types/jquery/test/val.ts",
          "kind": "test"
        },
        {
          "path": "types/jquery/tsconfig.json",
          "kind": "package-meta-ok"
        }
      ],
      "owners": [
        "leonard-thieu",
        "borisyankov",
        "choffmeister",
        "Steve-Fenton",
        "Diullei",
        "tasoili",
        "seanski",
        "Guuz",
        "ksummerlin",
        "basarat",
        "nwolverson",
        "derekcicerone",
        "AndrewGaspar",
        "seikichi",
        "benjaminjackman",
        "JoshStrobl",
        "johnnyreilly",
        "DickvdBrink",
        "King2500",
        "terrymun",
        "martin-badin",
        "princefishthrower"
      ],
      "addedOwners": [],
      "deletedOwners": [],
      "popularityLevel": "Critical"
    }
  ],
  "reviews": [
    {
      "type": "approved",
      "reviewer": "johnnyreilly",
      "date": "2023-10-04T19:26:26.000Z",
      "isMaintainer": true
    }
  ],
  "mainBotCommentID": 1732022687,
  "ciResult": "pass"
}

[typescript-bot]

🔔 @leonard-thieu @borisyankov @choffmeister @Steve-Fenton @Diullei @tasoili @seanski @Guuz @ksummerlin @basarat @nwolverson @derekcicerone @AndrewGaspar @seikichi @benjaminjackman @JoshStrobl @johnnyreilly @DickvdBrink @King2500 @terrymun @martin-badin @princefishthrower — please review this PR in the next few days. Be sure to explicitly select Approve or Request Changes in the GitHub UI so I know what's going on.

[typescript-bot]

Re-ping @leonard-thieu, @borisyankov, @choffmeister, @Steve-Fenton, @Diullei, @tasoili, @seanski, @Guuz, @ksummerlin, @basarat, @nwolverson, @derekcicerone, @AndrewGaspar, @seikichi, @benjaminjackman, @JoshStrobl, @johnnyreilly, @DickvdBrink, @King2500, @terrymun, @martin-badin, @princefishthrower:

This PR has been out for over a week, yet I haven't seen any reviews.

Could someone please give it some attention? Thanks!

[Steve-Fenton]

Hey @andersk - I couldn't see an example in your tests that demonstrates the HTML Input case you mention in the description. I might just be missing it. I can see you handling the scenarios for single and multi-selected, but not the one that demonstrates the input with the expected string | null type.

[andersk]

@Steve-Fenton We never expect string | null; I assume you mean string | undefined. That’s the first test case, and it includes HTMLInputElement on line 4.

DefinitelyTyped/types/jquery/test/val.ts

Lines 1 to 10 in 5b98d04

	let string_val: string | undefined = $<
	| HTMLButtonElement
	| HTMLDataElement
	| HTMLInputElement
	| HTMLOptionElement
	| HTMLOutputElement
	| HTMLParamElement
	| (HTMLSelectElement & { type: 'select-one' })
	| HTMLTextAreaElement
	>('button, data, input, option, output, param, select:not([multiple]), textarea').val();

[Steve-Fenton]

@andersk Yep. I missed it! Thanks for that.

[Steve-Fenton]

@johnnyreilly this looks okay to me!

[typescript-bot]

@andersk: Everything looks good here. I am ready to merge this PR (at 5b98d04) on your behalf whenever you think it's ready.

If you'd like that to happen, please post a comment saying:

Ready to merge

and I'll merge this PR almost instantly. Thanks for helping out! ❤️

(@leonard-thieu, @borisyankov, @choffmeister, @Steve-Fenton, @Diullei, @tasoili, @seanski, @Guuz, @ksummerlin, @basarat, @nwolverson, @derekcicerone, @AndrewGaspar, @seikichi, @benjaminjackman, @JoshStrobl, @johnnyreilly, @DickvdBrink, @King2500, @terrymun, @martin-badin, @princefishthrower: you can do this too.)

[andersk]

Ready to merge