Tutorial Server

Hi everyone!

This is a standalone server for the javascript tutorial https://javascript.info.

You can use it to run the tutorial locally and translate it into your language.

Windows, Unix systems and macOS are supported. For Windows, you'll need to call scripts with ".cmd" extension, that are present in the code alongside with Unix versions.

Installation

1. Install Git and Node.js.

   These are required to update and run the project. For Windows just download and install, otherwise use standard OS install tools (packages or whatever convenient).

   Please use Node.js 10+.

   (Maybe later, optional) If you're going to change images, please install ImageMagick.

2. Install global Node modules:

   npm install -g bunyan gulp@4

3. Create the root folder.

   Create a folder /js for the project.

   You can also use another directory as the root, then change the paths below: replace /js with your root.

4. Clone the tutorial server into it:

   cd /js
   git clone https://github.com/javascript-tutorial/server
   git clone https://github.com/javascript-tutorial/engine server/modules/engine

   Please note, there are two clone commands. That's not a typo: modules/engine is cloned from another repository.

   And please don't forget this when updating, modules/engine needs to be fetched and merged too.

5. Clone the tutorial text into it.

   The repository starts with the language code, e.g for the French version fr.javascript.info, for Russian – ru.javascript.info etc.

   The English version is en.javascript.info.

   The tutorial text repository should go into the repo subfolder, like this:

   cd /js/server/repo
   git clone https://github.com/javascript-tutorial/en.javascript.info

6. Run the site

   Install local NPM modules:

   cd /js/server
   npm install

   Run the site with the ./edit command with the language argument. Above we cloned en tutorial, so:

   ./edit en

   This will import the tutorial from /js/server/repo/en.javascript.info and start the server.

   Wait a bit while it reads the tutorial from the disk and builds static assets.

   Then access the site at http://127.0.0.1:3000.

   To change the port, set the PORT environment variable:

   # Runs the server at http://127.0.0.1:8080
   PORT=8080 ./edit en

   For Windows, read the note about environment variables below.

7. Edit the tutorial

   As you edit text files in the tutorial text repository (cloned at step 5), the webpage will reload automatically.

Windows: Environment variables

For Windows, to pass environment variables, such as PORT, you can install npm i -g cross-env and prepend calls with cross-env, like this:

cd /js/server
cross-env PORT=8080 ./edit en

In the examples below, the commands are without cross-env, prepend it please, if you're on Windows.

Alternatively, you can use other Windows-specific ways to set environment variables, such as a separate set PORT=8080 command.

Change server language

The server uses English by default for navigation and design.

You can set another language it with the second argument of edit.

E.g. if you cloned ru tutorial, it makes sense to use ru locale for the server as well:

cd /js/server
./edit ru ru

Please note, the server must support that language. There must be corresponding locale files for that language in the code of the server, otherwise it exists with an error. As of now, ru, en, zh, tr, ko and ja are fully supported.

Translating images

Please don't translate SVG files manually.

They are auto-generated from the English variant, with the text phrases substituted from images.yml file in the repository root, such as https://github.com/javascript-tutorial/ru.javascript.info/blob/master/images.yml.

So you need to translate the content of images.yml and re-generate the SVGs using a script.

Here are the steps to translate images.

Make sure you have installed ImageMagick mentioned in the installation step

Step 1. Create images.yml with translations in the repository root.

An example of such file (in Russian): https://github.com/javascript-tutorial/ru.javascript.info/blob/master/images.yml

The file format is YAML.

Here's a quote:

code-style.svg:  # image file name
  "No space":    # English string
    text: "Без пробелов" # translation
    position: "center" # (optional) "center" or "right" - to position the translated string

As you can see, for each image file (such as code-style.svg), there go English phrases (such as "No space").

For each phrase, there's the translated text and the text position (not always needed, details will come soon).

You can make a small file with only one image for the start.

Step 2. Setup git upstream (if you haven't yet) and pull latest changes from English version:

cd /js/server/repo/zh.javascript.info # in the tutorial folder

git remote add upstream https://github.com/javascript-tutorial/en.javascript.info

git fetch upstream master

Step 3. With the help of script imageYaml, check the existing texts of the image you want to translate, for example to the code-style.svg file, when executing the command, you will get the following results:

# Adjust NODE_LANG to your language

❯ NODE_LANG=en npm run gulp -- engine:koa:tutorial:imageYaml --image code-style.svg

# Remainder of log omitted …

Processing image code-style.svg
code-style.svg:
  '2': ''
  No space: ''
  between the function name and parentheses: ''
  between the parentheses and the parameter: ''
  Indentation: ''
  2 spaces: ''
  teste a: ''
  after for/if/while…: ''
  '} else { without a line break': ''
  Spaces around a nested call: ''
  An empty line: ''
  between logical blocks: ''
  Lines are not very long: ''
  A semicolon ;: ''
  is mandatory: ''
  Spaces: ''
  around operators: ''
  Curly brace {: ''
  on the same line, after a space: ''
  A space: ''
  between: ''
  arguments: ''
  A space between parameters: ''

It is possible to notice that the script returns a list of a set of words, which separately form the snippet that can be translated. To succeed in the translation, it is necessary to configure the snippet as close as possible to what the script expects.

Let's take as an example the text '} else { without a line break', in which it is necessary to pay attention to two observations:

1. The single quotes at the beginning and at the end are not part of the excerpt, as they only surround the set of words. It may be that in some scenarios it appears in the middle of the snippet (for example, What's), for such a scenario it is necessary to use it in the configuration, but the example taken is different, and that is why we will not consider the single quote at the beginning and at the end of the text.
2. There is a set of characters for which there is no translation or there is no need (for example, } else {), however, it is necessary to register them with part of the text to be translated, otherwise the script will not identify the need for translation.

Finally, we will have the following configuration to succeed in the translation:

code-style.svg:
  "} else { without a line break": 
  	text: "} else { xxxxxxx x xxxx xxxxx"

Note

• You may come across special characters, so the script returns the strings with code formatting, if applicable, configure the representation of the character visually, for example: double quotes " (visual) will be returned by script as " (code).
• If you encounter problems related to the size of the translated text being too different from the original text, see the section The "Text Overflowing" and test without using the position parameter (maybe trying to center, for example, is interfering).
• For other translation issues, see the section Troubleshooting image translation.

Step 4. Run the translation task:

cd /js/server # in the server folder

# adjust NODE_LANG to your language

NODE_LANG=zh npm run gulp -- engine:koa:tutorial:figuresTranslate

This script checks out all SVG images from upstream (English version) and replaces the strings inside them according to images.yml. So they become translated.

The new translated SVGs are the tutorial folder now, but not committed yet.

You can see them with git status.

Take a moment to open and check them, e.g. in Chrome browser, just to ensure that the translation looks good.

P.S. If an image appears untranslated on refresh, force the browser to "reload without cache" (hotkeys).

Step 5. Then you'll need to git add/commit/push the translated SVGs, as a part of the normal translation flow.

...And voilà! SVGs are translated!

Normally, the translation script looks for all images listed in images.yml. To translate a single image, use the --image parameter of the script:

# replace strings only in try-catch-flow.svg
NODE_LANG=zh npm run gulp -- engine:koa:tutorial:figuresTranslate --image try-catch-flow.svg

Positioning

By default, the translated string replaces the original one, starting in exactly the same place of the image.

Before the translation:

| hello world

After the translation (你 is at the same place where h was, the string is left-aligned):

| 你好世界

Sometimes that's not good, e.g. if the string needs to be centered, e.g. like this:

     |
hello world
     |

(The "hello world" is centered between two |).

Then, if we just replace the string, it would become:

     |
你好世界
     |

As we can see, the new phrase is shorter. We should move it to the right a bit.

The position: "center" in images.yml does exactly that.

It centers the translated string, so that it will replace the original one and stay "in the middle" of the surrounding context.

Here's the text with position: "center", centered as it should be:

   |
你好世界
   |

The position: "right" makes sure that the translated string sticks to the same right edge:

hello world |
    你好世界 |

That's also useful for images when we expect the text to stick to the right.

P.S In order for positioning to work, you need to have ImageMagick installed: https://imagemagick.org/script/download.php (or use packages for Linux or homebrew/macports for MacOS).

Helper script: extract strings

The task to get all strings from an image as YAML (for translation, to add to images.yml):

cd /js/server # in the server folder

NODE_LANG=zh npm run gulp -- engine:koa:tutorial:imageYaml --image code-style.svg

It extracts all text lines and outputs as a template for the images.yml.

Useful for debugging, when the translation doesn't "catch up", because the SVG text has an extra space or so.

The "overflowing text" problem

The replacement script only operates on strings, not other graphics, so a long translated string may not fit the picture.

Most pictures have some extra space for longer text, so a slight increase doesn't harm.

If the translated text is much longer, please try to change it, make it shorter to fit.

If the translated text absolutely must be longer and doesn't fit, let me know, we'll see how to adjust the picture.

Troubleshooting images translation

If you add a translation to images.yml, but after running the script the SVG remains the same:

1. Ensure that you have the latest server code and translation repos, fetched the upstream.

2. Check if the English version has the file with the same name. The file could have been renamed.

3. Check that there's only 1 file with the given name in the tutorial. Sometimes there may be duplicates.

4. Check that the translated string in images.yml is exactly as in SVG: use the helper script to extract all strings.

   For example, let's say you added "White Rabbit": "Coelho Branco" to the images.yml for proto-constructor-animal-rabbit.svg file, and it doesn't work.

   Let's get all strings:

   ❯ NODE_LANG=pt npm run gulp -- engine:koa:tutorial:imageYaml --image proto-constructor-animal-rabbit.svg
   proto-constructor-animal-rabbit.svg:
       'eats: true': ''
       'name: "White Rabbit"': ''
       animal: ''
       Rabbit: ''
       rabbit: ''
       '[[Prototype]]': ''
       prototype: ''
   

   Now we can see, that the text in the SVG is actually longer, it's name: "White Rabbit".

   So the images.yml should translate it as a whole: "name: \"White Rabbit\"": ... (note: quotes are escaped).

If it still doesn't work – file an issue.

Dev mode

If you'd like to edit the server code (assuming you're familiar with Node.js), not the tutorial text, then there are two steps to do.

First, run the command that imports (and caches) the tutorial:

cd /js/server
NODE_LANG=en npm run gulp engine:koa:tutorial:import

For Windows: npm i -g cross-env and prepend the call with cross-env to pass environment variables, like this:

cd /js/server
cross-env NODE_LANG=en...

Afterwards, call ./dev <server language> to run the server:

cd /js/server
./dev en

Running ./dev uses the tutorial that was imported and cached by the previous command.

It does not "watch" tutorial text, but it reloads the server after code changes.

Again, that's for developing the server code itself, not writing the tutorial.

Troubleshooting

Please ensure you have Node.js version 10+ (node -v shows the version).

If it still doesn't work – file an issue. Please mention OS and Node.js version.

Please pull the very latest git code and install latest NPM modules before publishing an issue.

Linux: inotify and monitored files

The server's tools use inotify by default on Linux to monitor directories for changes. In some cases there may be too many items to monitor.

! Samples code below work correctly for Ubuntu.

You can get your current inotify files watch limit by:

$> cat /proc/sys/fs/inotify/max_user_watches

When this limit is not enough to monitor all files, you have to increase the limit for the server to work properly.

You can set a new limit temporary by:

$> sudo sysctl fs.inotify.max_user_watches=524288
$> sudo sysctl -p

It is very important that you refer to the documentation for your operating system to change this parameter permanently.

--
Yours,
Ilya Kantor
iliakan@javascript.info