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Effortless Nodemon Setup with TypeScript and ESM
Learn how to use Nodemon to automatically restart your Node.js app when you make changes to your TypeScript code. Install the necessary dependencies and configure Nodemon to watch your TypeScript files. Then, run your application using Nodemon for a faster development experience.
Ready to supercharge your Node.js development? Nodemon's got your back! In this tutorial, we'll show you how to set up Nodemon to automatically restart your Node.js app when you make changes to your TypeScript code. Get ready for a faster, smoother development experience.
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Install Development Dependencies
We include the following development dependencies: TypeScript, nodemon, ts-node, and the essential type definitions for Node.js. Use this command to install them:
The ts-node
package performs Just-In-Time (JIT) transformations, converting TypeScript into JavaScript. This allows you to execute TypeScript directly in Node.js without the need for precompilation. It comes with two executables: ts-node
for running CommonJS packages and ts-node-esm
for running ESM packages.
Here's an example of how to launch an ESM module from its main entry point using ts-node-esm
:
Alternatively, you can invoke Node directly and instruct it to load ts-node
for you using the following command:
This will allow you to pass additional configuration to parameters like max_old_space_size
to Node's process:
Note: You also have to use node --loader ts-node/esm
instead of ts-node-esm
when you get to see this error message:
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for ...
This is particularly the case when using ECMAScript modules instead of CommonJS packages.
Connect ts-node with nodemon
Now that we've covered how ts-node
works, let's improve your development workflow by integrating nodemon. Nodemon will watch our TypeScript files for changes and automatically reload our code using the most recent modifications, all while running it through ts-node
. To achieve this, we need to create a nodemon.json
configuration file in the root directory of our project:
The configuration is easy to read. It instructs nodemon
to watch all files within the "src" directory that have a "ts" extension. When such file is found, nodemon will restart the running process using a command we've specified in our execution map (execMap). This map can hold different commands for various file types, but we're only interested in TypeScript files.
Now we can run our application using nodemon, which will operate based on the specified underlying configuration:
If you find the "ExperimentalWarning: Custom ESM Loaders is an experimental feature and might change at any time" warning annoying, you can disable it by making a change in the execMap
:
Another option is to use ts-node-esm
directly: