Show the difference in methods use to namespace functions in const

const_module_arrow_vs_function.ts

const WithFunc = {
    description: "Hello",
    classicFunction() {
        console.log(this.description, "description") // works but can lead to 'this' confusion
        return "classicFunction"
    }
}

const WithConst = {
    description: "Hello",
    arrowFunction: () => {
        console.log(WithConst.description, "description") // need to reference const
        return "arrowFunction"
    }
}

console.log(classicFunction()) // this works
    
function classicFunction() {
    return "classicFunction"
}

// this doesn't works; const not initialized yet
// console.log(arrowFunction())

// but this works fine because when it's called, arrowFunction is initialized
// this would be the case if this module was exported
const useArrowFunction = () => arrowFunction()

const arrowFunction = () =>  {
    return "arrowFunction"
}

console.log(useArrowFunction())

One advantage of using function on line 19 is that it gets hoisted to top. A forward reference will work:

oldSchoolFunction("Hello");

function oldSchoolFunction(msg) {
  console.log(msg)
}

The same will not work for const arrow function:

arrowFunction("Hello"); // throws not found

const arrowFunction = (msg) =>  console.log(msg)

However, if arrowFunction is called from another const or function (which is typically how you'd do it) then it's fine.

You can try this code out on typescriptlang.org