Resolve the error message "Class is not a constructor" which arises while utilizing namespaces in TypeScript with WebPack

Question

Resolve the error message "Class is not a constructor" which arises while utilizing namespaces in TypeScript with WebPack

Issue with TypeScript Namespaces in PIXI.js
As I delve into the world of TypeScript and PIXI.js without any framework, I find myself facing a challenge. Previously, at work, we utilized namespaces with the module keyword for a cleaner structure. However, when attempting to replicate this setup in my current project, I encountered an error upon running the code in the browser.

The Challenge
The error message that surfaces in the console reads: "Uncaught TypeError: MyApp.AbstractModel is not a constructor" while pointing to a specific line in Main.ts file.

Troubleshooting & Solutions Attempted
Despite referencing the TypeScript documentation on Namespaces multiple times, I struggle to identify the root cause of the issue. Initially, I suspected webpack to not load all files properly, but after implementing suggestions from a Stack Overflow thread, including using 'require.context()', the error persists. Additionally, I experimented with importing the namespace directly in the main file, but to no avail.

Folder Structure
To provide some context, here is a glimpse of my project's directory structure:

stack-overflow-example
| - .idea
| - dev
| | - dts
| | | <all .d.ts files from tsc compilation>
| | - js
| | | <all .js files and accompanying .js.map files from compiled .ts files>
| | - index.html
| - node_modules
| - src
| | - graphics
| | | - pixi-manager.ts
| | - model
| | | - AbstractModel.ts
| | - Main.ts
| | - refs.ts
| package.json
| package-lock.json
| tsconfig.json
| webpack.config.js

Looking for Solutions
If anyone has insights on resolving the "MyApp.AbstractModel is not a constructor" error without migrating to modules, your assistance would be invaluable. Thank you for taking the time to help out.

typescript webpack webpack-dev-server pixi.js tsc

Answer 1

Answer №1

Begin by investigating the root cause of the is not a constructor error: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Not_a_constructor. It appears that the issue may stem from AbstractModel not being defined at the point of error occurrence.

You can verify this using the following method:

        protected createModel(): void {
            console.log(typeof AbstractModel);
            this.model = new AbstractModel();
        }

If this is indeed the case, consider reframing your inquiry to something like: "How can classes be loaded from a directory in TypeScript and WebPack?".

In such a scenario, you can achieve the desired outcome through utilizing the require.context(... approach detailed here: Is it possible to import modules from all files in a directory, using a wildcard?

HOWEVER, make sure to review the following resources as well:

How to import all modules from a directory in TypeScript?
Typescript: export all functions in a namespace
- ^ Why is "import *" bad?
Considerations outlined in the In practice section of this answer: Is it possible to import modules from all files in a directory, using a wildcard?

Note that while this approach is viable, some individuals perceive it as suboptimal. Personally, I advocate for explicitly specifying dependencies within each file for clarity and enhanced IDE support.

Another issue to address pertains to the comparison between <reference path... and import usage. Initially favoring brevity with an array of imports, your practice in refs.ts resorts to numerous reference statements, mirroring the line count attributed to traditional imports.

To further understand this discrepancy, revisit the example cited in the documentation linked in your query: https://www.typescriptlang.org/docs/handbook/namespaces.html#multi-file-namespaces. Notably, each necessary file includes a <reference directive in Test.ts:

/// <reference path="Validation.ts" />
/// <reference path="LettersOnlyValidator.ts" />
/// <reference path="ZipCodeValidator.ts" />

...

Upon examining LettersOnlyValidator.ts and ZipCodeValidator.ts, both files are obliged to include

/// <reference path="Validation.ts" />

; notably, this dependency fails to propagate transitively – underscoring limitations associated with a "reference path approach".

In light of these insights, reassess adopting an import (and/or export) strategy where appropriate.

Typescript ///<reference path=“…”> and "Uncaught ReferenceError: exports is not defined"

Answer 2

Begin by investigating the root cause of the is not a constructor error: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Not_a_constructor. It appears that the issue may stem from AbstractModel not being defined at the point of error occurrence.

You can verify this using the following method:

        protected createModel(): void {
            console.log(typeof AbstractModel);
            this.model = new AbstractModel();
        }

If this is indeed the case, consider reframing your inquiry to something like: "How can classes be loaded from a directory in TypeScript and WebPack?".

In such a scenario, you can achieve the desired outcome through utilizing the require.context(... approach detailed here: Is it possible to import modules from all files in a directory, using a wildcard?

HOWEVER, make sure to review the following resources as well:

How to import all modules from a directory in TypeScript?
Typescript: export all functions in a namespace
- ^ Why is "import *" bad?
Considerations outlined in the In practice section of this answer: Is it possible to import modules from all files in a directory, using a wildcard?

Note that while this approach is viable, some individuals perceive it as suboptimal. Personally, I advocate for explicitly specifying dependencies within each file for clarity and enhanced IDE support.

Another issue to address pertains to the comparison between <reference path... and import usage. Initially favoring brevity with an array of imports, your practice in refs.ts resorts to numerous reference statements, mirroring the line count attributed to traditional imports.

To further understand this discrepancy, revisit the example cited in the documentation linked in your query: https://www.typescriptlang.org/docs/handbook/namespaces.html#multi-file-namespaces. Notably, each necessary file includes a <reference directive in Test.ts:

/// <reference path="Validation.ts" />
/// <reference path="LettersOnlyValidator.ts" />
/// <reference path="ZipCodeValidator.ts" />

...

Upon examining LettersOnlyValidator.ts and ZipCodeValidator.ts, both files are obliged to include

/// <reference path="Validation.ts" />

; notably, this dependency fails to propagate transitively – underscoring limitations associated with a "reference path approach".

In light of these insights, reassess adopting an import (and/or export) strategy where appropriate.

Typescript ///<reference path=“…”> and "Uncaught ReferenceError: exports is not defined"

Resolve the error message "Class is not a constructor" which arises while utilizing namespaces in TypeScript with WebPack

Answer №1

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