When do we put ( ) in export function in JavaScript?-CodePudding

When do we put ( ) in export function in JavaScript? like what is the difference between these code:

function Hello() {
 return "Hello World"
}
export Hello

and

function Hello() {
 return "Hello World"
}
export Hello()

CodePudding user response：

When you use this

function Hello() {
 return "Hello World"
}
export Hello

you are exporting your function.. therefore when you import it

import {Hello} from "hello.js"

console.log(typeof Hello) // "function"

console.log(Hello()) // "Hello World"

if you use this:

function Hello() {
 return "Hello World"
}
export Hello()

you are calling Hello function, and exporting its returning value, but you need to assign it to variable, or export it as default

function Hello() {
 return "Hello World"
}
export default Hello()

function HelloFc() {
 return "Hello World"
}
export const Hello = HelloFc()

and then import will look like this

import {Hello} from "hello.js"

console.log(typeof Hello) // "string"

console.log(Hello()) // Uncaught TypeError: "Hello" is not a function

CodePudding user response：

Basically both are not working!

If you want to export function Hello, let's use export { Hello }.

If you want to export return value of Hello function, let's use export default Hello().