Case sensitive issue in node.js - node.js

Question

I have 2 files,
extendableError.js
class ExtendableError extends Error {
constructor(message) {
super(message)
this.name = this.constructor.name
this.message = message
if (typeof Error.captureStackTrace === 'function') {
Error.captureStackTrace(this, this.constructor)
} else {
this.stack = new Error(message).stack
}
}
}
module.exports = ExtendableError
duplicatedError.js
const ExtendableError = require('./ExtendableError')
class DuplicatedError extends ExtendableError {
constructor(message) {
super(message)
}
}
module.exports = DuplicatedError
Below is my testing code,
const DuplicatedError = require('./duplicatedError');
const ExtendableError = require('./ExtendableError');
const ExtendableError1 = require('./extendableError');
try{
throw new DuplicatedError('hahah');
}catch(err){
console.log(err instanceof ExtendableError); // true
console.log(err instanceof ExtendableError1); // false
}
The test is on my mac book, why is that happen? Only the 1st charater was uppercase has different results. i don't understand.

Answer 1

Macs are based on BSD UNIX, so the file system is case sensitive.
As a side note, it’s common to not use camecase for file names, eg:
var extendableError = require(‘./extendable-error’)

Answer 2

Firstly, for compatibility reason, macOS chose a case-insensitive file system. But it doesn't mean you have to bear it, Disk Utility can be used to reformat the partition to case-sensitive mode. If You do that, node.js will report error to you because of the wrong module name you are trying to require.
Then, let's talk about your test result. The key issue is which one you require in duplicatedError.js, if you change it a little bit:
//change the required name to lowercase extendableError
const ExtendableError = require('./extendableError')
class DuplicatedError extends ExtendableError {
constructor(message) {
super(message)
}
}
module.exports = DuplicatedError
The test result will be:
false
true
You can even try to modify duplicatedError.js like below:
//change the required name to extENDableError
const ExtendableError = require('./extENDableError')
class DuplicatedError extends ExtendableError {
constructor(message) {
super(message)
}
}
module.exports = DuplicatedError
The result shall be
false
false
So i think it's not about module caching, you have two things to be clear here:
macOX is case-insensitive file system by default
even you have only one file extendableError.js, but you require twice with different names, like: require(./extendableError), require(./ExtendableError), require(./extENDableError), trey will be treated as three modules.