Run TypeScript Without Compiling

Introduction

In this post, I will show you how to run TypeScript without compiling it to JavaScript. This is useful for debugging and testing. In this post, I will show you how to do it.

Setup a TypeScript Project

Step 1: Create a Directory

Create a directory for the project.

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# Create a directory
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mkdir run-typescript-without-compiling
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# Change directory
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cd run-typescript-without-compiling

Step 2: Initialize a Node.js Project

Initialize a Node.js project.

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# Initialize a Node.js project
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yarn init -y

Step 3: Install TypeScript and @types/node

Install TypeScript and @types/node.

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# Install TypeScript and @types/node
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yarn add -D typescript @types/node

Step 4: Initialize a TypeScript Project

Initialize a TypeScript project.

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# Initialize a TypeScript project
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yarn tsc --init

Step 5: Create a TypeScript File

Create a TypeScript file.

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# Create a src directory
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mkdir src
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# Create a TypeScript file
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touch src/index.ts

Step 6: Example Code

Add the following code to the TypeScript file.

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const sum = (a: number, b: number): number => a + b;
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const subtract = (a: number, b: number): number => a - b;
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const multiply = (a: number, b: number): number => a * b;
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const divide = (a: number, b: number): number => a / b;
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console.log(sum(1, 2));
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console.log(subtract(1, 2));
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console.log(multiply(1, 2));
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console.log(divide(1, 2));

Step 7: Run the TypeScript File

Now, we will install ts-node and run the TypeScript file.

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# Install ts-node
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yarn add -D ts-node

Add the following code to the package.json file.

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{
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  ...
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  "scripts": {
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    "playground": "ts-node src/index.ts",
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    "playground:watch": "nodemon -e ts -w . -x esr src/index.ts",
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    "build": "tsc",
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    "build:watch": "tsc -w",
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    "build:debug": "tsc --sourceMap",
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    "build:debug:watch": "tsc -w --sourceMap",
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    "start": "node dist/index.js",
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    "start:watch": "nodemon -e js -w dist -x esr dist/index.js"
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  },
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  ...
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}

Run the TypeScript file.

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# Run the TypeScript file
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yarn playground
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# Output
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3
6
-1
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2
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0.5

Conclusion

I demonstrated how to run TypeScript in this article without converting it to JavaScript. For testing and troubleshooting, this is helpful. I demonstrate how to accomplish that in this post.

References

• TypeScript Official Website
• TypeScript Documentation
• ts-node on npm
• ts-node GitHub Repository (TypeStrong/ts-node)
• nodemon on npm
• nodemon Official Website
• Node.js Official Website
• Node.js Documentation
• Yarn Package Manager
• TypeScript tsconfig.json Reference
• npm package.json Guide
• @types/node package on npm (for Node.js type definitions)
• TypeScript Playground (for quick experiments)