P5.js 2.0 Bug: Typescript Global Mode Import Issue

Introduction

In the world of creative coding, p5.js stands out as a versatile JavaScript library for artists, designers, educators, and beginners. It simplifies the process of creating interactive graphics and animations in the browser. Recently, a bug report surfaced regarding p5.js version 2.0, specifically concerning its interaction with TypeScript in global mode. This issue affects developers who rely on TypeScript for type safety and maintainability in their p5.js projects. Understanding this bug and its workaround is crucial for developers aiming to leverage the power of p5.js with TypeScript.

This article will delve into the specifics of the bug, the steps to reproduce it, the current workaround, and potential solutions. Whether you're an experienced p5.js user or just starting, this guide will provide valuable insights into addressing this import issue and ensuring a smooth development experience.

The Bug: Separate Imports Required in Global Mode

The core of the issue lies in how p5.js 2.0 handles TypeScript imports when working in global mode. In global mode, p5.js functions and variables are expected to be available in the global scope, making it easier to write code without explicitly importing every function. However, when using TypeScript, this approach leads to a problem: the type definitions for p5.js are not automatically recognized in the global scope. This discrepancy between runtime behavior and type-checking expectations results in errors and a less-than-ideal development experience.

Specifically, the bug manifests in two primary ways:

1. Runtime Error: When importing "p5/global" and attempting to use p5.js functions, a ReferenceError: p5 is not defined error may occur in the browser console. This indicates that the p5 object is not correctly exposed in the global scope at runtime.
2. Type-Checking Failure: When importing p5 from "p5/global", the code runs in the browser, but type-checking fails. The TypeScript compiler does not recognize properties like Vector on the p5 object, leading to type errors. This undermines the benefits of using TypeScript for static analysis and error prevention.

Steps to Reproduce the Bug

To reproduce this bug, follow these steps:

1. Set up a TypeScript project with Node.js: Initialize a new Node.js project and configure TypeScript.

2. Install p5.js: Install the p5.js package version 2.1.1 (or later) using npm or yarn: npm i -D p5 or yarn add -D p5.

3. Create a TypeScript sketch: Add a TypeScript file (e.g., sketch.ts) with the following snippet:

   import "p5/global";
   
   window.setup = function setup() {
       createCanvas(200, 200);
       console.log(p5.Vector.random2D());
   };
   

4. Run the sketch in a browser via a development server: Use a tool like webpack-dev-server or parcel to serve the project in a browser.

5. Observe the runtime error: Open the browser's developer console and observe the ReferenceError: p5 is not defined error.

Alternative Attempt

Alternatively, try the following snippet:

import p5 from "p5/global";

window.setup = async function setup() {
    createCanvas(200, 200);
    console.log(p5.Vector.random2D());
};

In this case, the code will run in the browser, but type-checking will fail because TypeScript does not recognize the Vector property on p5.

Current Workaround: Separate Imports

Currently, the workaround for this issue involves using separate imports for the global p5.js environment and the p5 object. This means importing "p5/global" to make p5.js functions available globally and importing p5 from "p5" to provide TypeScript with the necessary type definitions.

The workaround looks like this:

import "p5/global";
import p5 from "p5";

window.setup = function setup() {
    createCanvas(200, 200);
    console.log(p5.Vector.random2D());
};

While this workaround resolves both the runtime error and the type-checking failure, it introduces a less-than-ideal developer experience. TypeScript may flag the second import (import p5 from "p5") as unused if the p5 variable is not directly used in the code (e.g., if only global functions like createCanvas and p5.Vector are used). This can lead developers to remove the import, which then causes type-checking errors when they later attempt to use p5-specific properties or functions.

A Cleaner Solution: Modifying global.d.ts

A more elegant solution, as suggested by @davepagurek on Discord, involves modifying the global.d.ts file within the p5.js package. This file contains the type definitions for the global p5.js environment. By adding export default p5 at the end of this file, the p5 object is correctly exposed as a default export, allowing for a single, clean import statement.

To implement this solution:

1. Locate global.d.ts: Find the global.d.ts file in the node_modules/p5/global.d.ts directory.

2. Modify the file: Open global.d.ts in a text editor and add the following line at the end of the file:

   export default p5;
   

3. Use a single import: In your TypeScript sketch, use the following import statement:

   import p5 from "p5/global";
   
   window.setup = function setup() {
       createCanvas(200, 200);
       console.log(p5.Vector.random2D());
   };
   

With this modification, type-checking and runtime availability of the p5 variable are both resolved with a single import. This approach provides a more intuitive and less error-prone development experience.

Caveats of Modifying node_modules

It's important to note that modifying files directly within the node_modules directory is generally discouraged. Changes made in node_modules are not persistent and will be overwritten when dependencies are updated or reinstalled. Therefore, this solution is best considered a temporary workaround or a local fix for development purposes.

For a more permanent solution, it's recommended to contribute the fix to the p5.js library itself, so it can be included in future releases. This ensures that all users can benefit from the improved TypeScript integration.

Impact on Development Workflow

This bug and its workaround can significantly impact the development workflow for p5.js projects using TypeScript. The need for separate imports or manual modification of type definition files adds complexity and potential for errors. Developers may spend unnecessary time troubleshooting import issues instead of focusing on creative coding.

By addressing this bug, the p5.js community can enhance the developer experience and make it easier for TypeScript users to leverage the library's capabilities. A streamlined import process reduces friction and allows developers to focus on creating compelling interactive graphics and animations.

Community Discussion and Potential Solutions

The p5.js community is actively discussing this bug and potential solutions. The original bug report has sparked conversations among developers and maintainers, leading to proposals for fixing the issue in future releases. Some of the suggested solutions include:

1. Updating the global.d.ts file in the p5.js package: As discussed earlier, adding export default p5 to global.d.ts is a straightforward fix that addresses both runtime and type-checking issues.
2. Revising the p5.js module structure: A more comprehensive solution might involve restructuring the p5.js modules to better align with modern JavaScript module conventions and TypeScript's type-checking mechanisms. This could involve changes to how p5.js functions are exposed in the global scope and how type definitions are generated and distributed.
3. Providing clearer documentation and examples: Improving the documentation and providing clear examples of how to use p5.js with TypeScript can help developers avoid common pitfalls and quickly resolve import issues.

Conclusion

The p5.js 2.0 bug related to TypeScript imports in global mode presents a challenge for developers seeking to combine the creative power of p5.js with the type safety of TypeScript. While the current workaround of using separate imports addresses the issue, it introduces some friction into the development process. A more elegant solution involves modifying the global.d.ts file to correctly expose the p5 object as a default export.

The p5.js community is actively working on addressing this bug, and future releases are expected to include a more seamless integration with TypeScript. In the meantime, developers can use the workaround or the global.d.ts modification to continue building amazing interactive graphics and animations with p5.js and TypeScript.

By staying informed about these issues and actively participating in community discussions, developers can contribute to the ongoing improvement of p5.js and ensure a smooth development experience for themselves and others.

For more information on p5.js and its capabilities, visit the official p5.js website.