/gas-custom

Google App Scripts Custom Applications

Primary LanguageTypeScriptMIT LicenseMIT

Google Apps & TypeScript Project Template

Note: The GitHub Workflows build will always be failing for this template repo as it doesn't have a package-lock.json file. This is intentional! When you run npm i for your project, just make sure to commit the lockfile.

This repository provides a simple template to start a new Google Apps Script project with TypeScript. Building, linting, formatting, and pushing to Google Apps are all built in.

The project is set up with a TypeScript configuration that transforms your TypeScript files in the src directory into JavaScript files in the build directory. It's not enough to upload those files as-is to Google Apps, however, because Apps Script doesn't support installing and running dependencies, and uploaded files are run in random order - they aren't linked together at all. To solve this problem, a second build step uses Webpack to combine all files and depdendencies into a single minified Code.js file, which is the only file that is actually pushed to Google Apps.

Getting Started

  1. Install Node.js.
  2. Click "Use This Template" to start a new repository. Clone your new repo and open a terminal in the local directory. This template includes some configuration for VSCode, but you can use any editor.
  3. Install all of the dependencies by running npm install.
  4. Start a new Google Apps Script project by going to https://script.google.com/home and clicking New Project. You can also start a project tied directly to a specific Google Apps file by opening the file and clicking Tools -> Script Editor.
  5. Click File -> Project Properties in the Google Apps Script editor. Enter a project name if prompted to, then on the Info tab in the Project Properties window, find and copy the Script ID.
  6. Replace SCRIPT_ID in .clasp.json with your project's ID. This ID is not a secret - you can safely commit it to your repository.
  7. Add your TypeScript code in the src folder. Note that unlike in a normal Google Apps Script project, only what is imported into the index.ts file will be compiled into the script, and all files must be in the src folder (except external dependencies).
  8. Optional: lint your code with npm run lint and/or auto-format your code with npm run format. Typically you will want to install the ESLint and/or Prettier extensions in your preferred code editor.
  9. Log in to Google Apps Script by running npm run login. Make sure to use the same account you used to make the Google Apps Script project.
  10. Compile the TypeScript files into a single JavaScript file and push it to Google Apps by running npm run push. Run this every time you make changes. If you ever change the project configuration (ie, by adding new APIs), you will need to sync the appsscript.json file by running npm run pull before you run npm run push.

Available Scripts

You can run the following scripts by opening the project directory in your terminal (as long as you have Node & npm installed):

  • npm install Install all required dependencies.
  • npm run build Build your project to ensure it compiles properly.
  • npm run format Format your code automatically using Prettier.
  • npm run lint Check your code for common errors using ESLint.
  • npm run login Login to the Google Apps Script client so you can push/pull. You will need to run this once on each device you use.
  • npm run pull Fetch the latest changes from Google Apps Script. You should only need to do this if you change the project settings.
  • npm run push Build your project and push it to Google Apps in one step. The first time you run this, you will be prompted to log in to your Google account.

Automated GitHub Workflow

The template comes with a built-in configuration file for GitHub Workflows. The workflow is configured to run on every push to the master branch as well as on every Pull Request as a Check, and it simply checks the code to ensure that it passes linting and is buildable (has no type/syntax errors). This is known as continuous integration and provides a form of automated testing to ensure that your project's code is always valid.

For larger projects where more than one developer will be collaborating, it is reccomended to protect the master branch and only allow changes to it through Pull Requests in which all checks pass. You can learn more about this from GitHub's help articles.

If you would like to disable the workflow, simply delete the checks.yml file.

Development Notes

The following notes have important information for writing code for Google Apps Script using this template. Please read through them before you start.

Important: Exposing Functions to Google Apps Script

In order for your Google Apps to run any of your code, you'll need to expose one or more functions to the engine. In the traditional Google Apps Script environment, you'd do this by declaring global functions, however in this setup there is no concept of 'global' as all files are modules.

Instead, you need to add these to the global object. This object type is declared in src/global.d.ts so you can assign to it from any file, although as a matter of best-practice you may want to confine global assignments to your index.ts file. Any function added to the global object will be available under that name to all triggers and anywhere else Google Apps might need to call your function, such as from a custom menu.

Note that the field in global that you assign the function, not the function's name, is treated as the function name. For example, the following function will be called by the onOpen trigger, not the onEdit trigger:

function onEdit() {}

global.onOpen = onEdit;

Further documentation is provided with the global type definition in global.d.ts and examples for all the simple triggers are given in index.ts.

Circular Dependencies

Circular dependencies (files that depend on each other in a circular manner) can cause unexpected issues like "X is not a function" or "X is not defined". If you are seeing these errors in your project and you know they are wrong, try checking for circular dependencies using madge (not included in this template):

  1. Install madge globally with npm i --global madge.
  2. Check for circular dependencies with madge src/index.ts --circular.

Included Files

  • .github
    • workflows All GitHub workflows are configured using YAML files in this directory.
      • checks.yml This is where the continuous integration workflow is configured.
  • src This is where you'll put all your TypeScript files.
    • example.ts Gives an example of how to export something from a local file.
    • index.ts Provides you with the five basic triggers prebuilt, as well as an example of how to import from a local file.
    • global.d.ts Provides type-definitions for the global object from which triggers are exported.
  • .clasp.json Provides the configuration for Clasp, the command-line tool which pushes code to Google Apps Script.
  • .claspignore Tells Clasp to ignore every file except for Code.js, appsscript.json, and readme_appsscript.md.
  • .gitignore Tells Git to ignore output files and node_modules.
  • .prettierrc Configures Prettier, the code formatter.
  • appsscript.json Controls the project setup and Apps Script environment. You can change the exception logger, but don't change the runtime version.
  • package.json Lists the project dependencies and scripts.
  • readme_appsscript.md If anyone opens your project in the Apps Script editor, they'll just see a jumbled file. This note helps them realize that the project should be edited outside of that environment.
  • readme.md This file.
  • tsconfig.json Configures the TypeScript compiler to enable strict mode and compile to CommonJS modules from the src folder to the build folder.
  • webpack.config.js Configures Webpack to take files from the build folder and dependencies and merge them all into a single Code.js file.