Intro
So we installed NodeJS on our machine.
Now we want to learn how to create our own module.
Write a simple script
- Open your terminal
- Create a file named
logger.js
:
touch logger.js
- Add this JavaScript code into it:
// the function should get a message type and a message
function logger(type, message) {
let format;
// different message for different message type
switch (type) {
case 'error':
format = `[ERROR] ${message}`;
break;
case 'success':
format = `[SUCCESS] ${message}`;
break;
default:
format = `${message}`;
break;
}
console.log(format);
}
// export the function using object property shorthand syntax
// to rename, use "newName: logger"
module.exports = {
logger
};
Note: For the sake of simplicity, this example is very lightweight, has no error/edge-case handling (e.g. no type), no separate file for the message types, no colors etc.
Write a second simple script
- Open your terminal
- Create a file named
index.js
:
touch index.js
- Add this JavaScript code into it:
// import the exported logger property
const { logger } = require('./logger.js');
// use the function
logger('error', 'This is an error message.');
logger('success', 'This is a success message');
Run it from the terminal
- Run it:
node index.js
- Result:
[ERROR] This is an error message.
[SUCCESS] This is a success message.
Next Steps
- Q: What happens, when you forget to add a
type
? How can you solve this? - Q: How can you improve this example by separating the message types into a constant?
- Q: How can you improve this example by using an object as parameter instead of two strings?
- Q: Do you need some additional error handling? (=> Docs)
Further Reading
Questions
- What is your favorite self-written module, that improves your developer life?
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