Unlike most other programming languages or runtime environments, Node.js doesn't have a built-in special main function to designate the entry point of a program. But there is an easy way to achieve this in Node.js, which we will show in this article.

The pattern is to check if the current module is the main module: require.main === module. If this is true, the current file has been run directly - as opposed to have been imported by another file - and in this case we can call the main function. Example:

// main.js / main.ts (the filename doesn't matter)

function main() {
  console.log("Hello world");
}

if (require.main === module) {
  main();
}

References

• Accessing the main module
• require.main
• The module object