-- node js is a javascript runtime environment that runs JS outside the web browser.
we can run node js in
-REPL ( read-eval-print-loop),
-CLI (command line interface)
COMMON JS MODULE :
DEFAULT EXPORTS:
--how to export one module also called (default exports) that allows us to export only one property.
{ const add = ()=> a+b;
module.exports = add ( exporting a module )
(add is a function that returns a value )
-- const add = require("./calculator") (importing a module)
-- importing from another module called calculator module to another one.
Note : "calculator" is a module name where add function is located.
}
NAMED EXPORTS:
--What if we need to export multiple functions at once
we use (named exports ) to export multiple properties
EXPORTING:
module.exports.add = add;
module.exports.sub = sub;
-we can also use shorthand for this -
exports.add = add;
exports.sub = sub;
--here we exported multiple functions from one module so we can use them in another module.
NOTE : if we don't export we can't use them in another module.
-IMPORTING:
{
-- When importing a module it returns an object
-- We can use obj destructing while importing multiple modules.
const cal = require("./calculator")
const {add, sub} = cal;
console.log(add(2, 3))
(calling a function from another module named calculator to another as shown above).
ES6 MODULES
In general, ES6 modules are considered to be a more modern and efficient way to modularize JavaScript code.
exporting modules:
default exports:
export default add;
(exporting only one function)
named exports
we can declare what we want to export before define a function.
export const add = (a,b) => a+b;
export const sub = (a,b) => a-b;
IMPORTING MODULES:
import {add , sub} from "./calculator.mjs"
NOTE: ES6-module is considered when that module extension ends with "mjs"
while importing we need to use an extension in order to import it.