User talk:The Transhumanist/P-link.js

This is the workshop support page for the user script P-link.js. Comments and requests concerning the program are most welcome. Please post discussion threads below the section titled Discussions. Thank you. By the way, the various scripts I have written are listed at the bottom of the page.

This script is under development, and is not yet fully functional

Script's workshop

This is the work area for developing the script and its documentation. The talk page portion of this page starts at #Discussions, below.

Description & instruction manual for P-link.js

This script is under development, and is not yet fully functional

When completed, this script will create 3 menu items:

P link on category

• if on category edit page it places corresponding portal link,
• if on category page it starts category edit page,
• otherwise it jumps to like-named category page

P link on template

• if on template edit page it places corresponding portal link,
• if on template page it starts template edit page,
• otherwise it jumps to like-named template page

P link on root

• if on article edit page it places corresponding portal link,
• if on article page it starts article edit page,
• otherwise jumps to like-named article page

The menu items are available on portal, category, template, and article pages.

This is a rudimentary version, and so it will require that the desired menu item be clicked on as a separate action up to 3 times. The goal is to use local storage so that link placement can be handled with a single click of the menu item.

How to install this script

Important: this script was developed for use with the Vector skin (it's Wikipedia's default skin), and might not work with other skins. See the top of your Preferences appearance page, to be sure Vector is the chosen skin for your account.

To install this script, add this line to your vector.js page:

importScript("User:The Transhumanist/P-link.js");

Save the page and bypass your cache to make sure the changes take effect. By the way, only logged-in users can install scripts.

Explanatory notes (source code walk-through)

This section explains the source code, in detail. It is for JavaScript programmers, and for those who want to learn how to program in JavaScript. Hopefully, this will enable you to adapt existing source code into new user scripts with greater ease, and perhaps even compose user scripts from scratch.

You can only use so many comments in the source code before you start to choke or bury the programming itself. So, I've put short summaries in the source code, and have provided in-depth explanations here.

My intention is Threefold:

1. to thoroughly document the script so that even relatively new JavaScript programmers can understand what it does and how it works, including the underlying programming conventions. This is so that the components and approaches can be modified, or used again and again elsewhere, with confidence. (I often build scripts by copying and pasting code that I don't fully understand, which often leads to getting stuck). To prevent getting stuck, the notes below include extensive interpretations, explanations, instructions, examples, and links to relevant documentation and tutorials, etc. Hopefully, this will help both you and I grok the source code and the language it is written in (JavaScript).
2. to refresh my memory of exactly how the script works, in case I don't look at the source code for weeks or months.
3. to document my understanding, so that it can be corrected. If you see that I have a misconception about something, please let me know!

In addition to plain vanilla JavaScript code, this script relies heavily on the jQuery library.

If you have any comments or questions, feel free to post them at the bottom of this page under Discussions. Be sure to {{ping}} me when you do.

General approach

(general approach goes here)

More specifically, starting at the beginning...

Aliases

An alias is one string defined to mean another. Another term for "alias" is "shortcut". In the script, the following aliases are used:

$ is the alias for jQuery (the jQuery library)

mw is the alias for mediawiki (the mediawiki library)

These two aliases are set up like this:

( function ( mw, $ ) {}( mediaWiki, jQuery ) );

That also happens to be a "bodyguard function", which is explained in the section below...

Bodyguard function

The bodyguard function assigns an alias for a name within the function, and reserves that alias for that purpose only. For example, if you want "t" to be interpreted only as "transhumanist".

Since the script uses jQuery, we want to defend jQuery's alias, the "$". The bodyguard function makes it so that "$" means only "jQuery" inside the function, even if it means something else outside the function. That is, it prevents other javascript libraries from overwriting the $() shortcut for jQuery within the function. It does this via scoping.

The bodyguard function is used like a wrapper, with the alias-containing source code inside it, typically, wrapping the whole rest of the script. Here's what a jQuery bodyguard function looks like:

1 ( function($) {
2     // you put the body of the script here
3 } ) ( jQuery );

See also: bodyguard function solution.

To extend that to lock in "mw" to mean "mediawiki", use the following (this is what the script uses):

1 ( function(mw, $) {
2     // you put the body of the script here
3 } ) (mediawiki, jQuery);

For the best explanation of the bodyguard function I've found so far, see: Solving "$(document).ready is not a function" and other problems   (Long live Spartacus!)

Load dependencies

Many of my scripts create menu items using mw.util.addPortletLink, which is provided in a resource module. Therefore, in those scripts it is necessary to make sure the supporting resource module (mediawiki.util) is loaded, otherwise the script could fail (though it could still work if the module happened to already be loaded by some other script). To load the module, use mw.loader, like this:

// For support of mw.util.addPortletLink
mw.loader.using( ['mediawiki.util'], function () {
// Body of script goes here.
} );

mw.loader.using is explained at mw:ResourceLoader/Core modules#mw.loader.using.

For more information, see the API Documentation for mw.loader.

The ready() event listener/handler

The ready() event listener/handler makes the rest of the script wait until the page (and its DOM) is loaded and ready to be worked on. If the script tries to do its thing before the page is loaded, there won't be anything there for the script to work on (such as with scripts that will have nowhere to place the menu item mw.util.addPortletLink), and the script will fail.

In jQuery, it looks like this: $( document ).ready(function() {});

You can do that in jQuery shorthand, like this:

$().ready( function() {} );

Or even like this:

$(function() {});

The part of the script that is being made to wait goes inside the curly brackets. But you would generally start that on the next line, and put the ending curly bracket, closing parenthesis, and semicolon following that on a line of their own), like this:

1 $(function() {
2     // Body of function (or even the rest of the script) goes here, such as a click handler.
3 });

This is all explained further at the jQuery page for .ready()

For the plain vanilla version see: http://docs.jquery.com/Tutorials:Introducing_$(document).ready()

Deactivation filters

Many scripts are written to work on a particular page or page type, and might have unexpected results if run on some other page. So a deactivation filter is used so the program does not run for the wrong pages.

For example:

    if (document.title.indexOf("Watchlist - Wikipedia") == -1) {
        // use a return statement to end the local function and hence the program's body
        // important: this approach does not work outside of a function
        return;
    }

What this if statement does is checks that the current page is not the one we want, and if that is true, we end the program via a return statement.

What return; does when alone like this (without any parameters), is to end the highest-level function which it is within. And since the body of the program is also within that function, if the if statement isn't true, the program ends.

You could do something similar with a straight if construct without "return;", checking for a page match, but then you'd have to have your whole script body inside the construct, which adds a level of indentation. The more filters, the more levels of indentation. The above approach avoids unnecessary indentation, and makes it easier to keep track of the curly brackets, as the closing bracket isn't way off at the end of the program.

var

This is the reserved word var, which is used to declare variables. A variable is a container you can put a value in. To declare the variable portletlink, write this:

var portletlink

A declared variable has no value, until you assign it one, such as like this:

portletlink = "yo mama";

You can combine declaration and assignment in the same statement, like this:

var portletlink = mw.util.addPortletLink('p-tb', '#', 'Remove red links');

Caveat: if you assign a value to a variable that does not exist, the variable will be created automatically. If it is created outside of a function, it will have global scope. For user scripts used on Wikipedia, having a variable of global scope means the variable may affect other scripts that are running, as the scripts are technically part of the same program, being called via import from a .js page (.js pages are programs). So, be careful. Here are some scope-related resources:

• The Horror of Implicit Globals
• Scope in JavaScript

Task list

Desired/completed features

Completed features are marked with  Done

Development notes for P-link.js

Rough rough talk-through

Further information: Pseudocode

The nature of scripts is that they run every time a page is loaded. One peculiarity with this script is that it loads pages. Once a new page loads, the script ends and starts over again on the loaded page.

The challenge is making the script pick up where it left off once it has loaded another page. Therefore, the script needs to ascertain what kind of page it is on and where in the process it is. Without tracking those things, the script will go into an endless loop.

First try

Upon the click of a single menu item (instead of 3), I'd like this program to

1. place a link to the current portal on the corresponding category page (if it isn't already there) and remove other (off-topic) portal links from that page
2. then place a link to the same portal on the corresponding root article page (if it exists) in its See also section, creating the section if there isn't one, and remove existing portal links
3. then place a link to the same portal at the bottom of the corresponding navbox footer page (if it exists), in the below= section, creating the section if there isn't one.

Second try

Does different stuff depending on what page it is on

1. Portal base page (has no "/" in title)
   1. Show menu item if title has "Portal:"
   2. Menu item doesn't show up if there is a "/"
   3. Store the name of the current portal (portalTitle).
2. Corresponding category edit page
   1. Check local storage = "went to category"
   2. Do search/replaces with regex
   3. Set local storage = "went to root"
   4. Goto root article edit page
3. Corresponding root article edit page
   1. Check local storage = "went to root"
   2. Do search/replaces with regex
   3. Set local storage = "went to navbox"
   4. Goto navbox edit page
4. Corresponding navbox footer edit page
   1. Check local storage = "went to navbox"
   2. Do search/replaces with regex

There's this script I've been working on...

It is now faster to build a portal than to place the links leading to it. So, I've been trying to write a link placer.

P-link stands for "portal link".

When completed, it will place links in 3 locations leading to a portal: on the corresponding category page, in the See also section of the corresponding article, and at the bottom of the corresponding navbox footer template. This will save loads of time, and should bring portal creation including link placement, down to under a minute for each portal.

I've got the "P link on category" menu item for placing the category page link working, sort of, but I had to resort to programming it to click the menu item up to 3 times instead of once, depending where you start from. I'd like it to work with one click from all of the allowed starting locations. It's a puzzle that has me stumped - working through the problem in my head or on paper with locally stored variables, I keep running into ambiguities discerning page types that I can't figure out. Once that problem is solved, I can move on to the other 2 menu items.    — The Transhumanist   02:59, 26 December 2018 (UTC)

P.S.:pinging @Certes and FR30799386:

@The Transhumanist: One way around this would be to, when the script loads the edit page, use something like ?action=edit&plink=yes. Then, for category edit pages, you check if the plink=yes is in the URL: If so, you skip to the code that inserts the portal; if not, you add the menu item that when clicked will do that.
As for determining page types, mw.config has a bunch of page-specific values that you can use, such as current action (like "edit" or "view"), namespace number, page title (both with and without the namespace prefix), categories (so you can check if page is in Category:All disambiguation pages or Category:All set index articles) – see mw:Manual:Interface/JavaScript#Page-specific. - Evad37 [talk] 14:35, 26 December 2018 (UTC)

The problem I kept getting was endless loops. The program couldn't tell the difference between the edit page and the preview page (which is also an edit page). So, the program would make the change and activate preview, but when the preview page came up, the script ran again. And again. And again. Etc.    — The Transhumanist   08:03, 27 December 2018 (UTC)

@The Transhumanist: mw.config.get('wgAction') will result in "edit" for the initial edit page, and "submit" for the preview edit page - Evad37 [talk] 08:17, 27 December 2018 (UTC)

Discussions

This is where the actual talk page starts for P-link.js. Please post your discussion threads below...