custom error detection

custom_error.js

class CustomError extends Error {
    constructor(...args) {
        super(...args)
        this.name = 'CustomError'
    }
}

const e1 = new CustomError('a custom error')
const e2 = new Error('a standard error')

if (e1 instanceof CustomError) {
    console.log('e1 is a CustomError')
} else {
    console.log('e1 is not a CustomError')
}

if (e2 instanceof CustomError) {
    console.log('e2 is a CustomError')
} else {
    console.log('e2 is not a CustomError')
}

// e1 is a CustomError
// e2 is not a CustomError