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Discussion on: There's no "else if" in JS

mahlongumbs profile image
Mahlon Gumbs • Edited on

Your information is not incorrect for regular functions. However, with an arrow function, you are allowed to use parentheses to represent a function body with a single statement (useful when spanning multiple lines).

There are other places you can omit things as well.


Single parameter, parentheses are optional

const myFunc = (singleParam) => {/* function body */};
// is the same as
const myFunc = singleParam => {/* function body */};

Multiple parameters require parentheses

const myFunc = (param1, param2) => {/* function body */};
const myFunc = param1, param2 => {/* function body */}; //Syntax error due to missing parentheses

Function body needs curly braces for multi-line command block

const myFunc = param1 => {
  console.log('I did something');
  console.log('I did something else');

However, if your body is a single line and you want to return the result, you may do any of the following (all of these return the value of name.toUpperCase()

const myFunc = name => {
  return name.toUpperCase(); // note the return

const myFunc = name => (
  name.toUpperCase(); // note, no return if in parentheses

const myFunc = name => name.toUpperCase();

It really helps if you have a command that spans multiple lines where you just want to return the result. So, for example, if you were dealing with a promise you could do either of the following:

const fetchUser = userId => (
    .then(rsp =>
    .catch(error => {

const fetchUser = userId => {
  return fetch(`${userId}`)
    .then(rsp =>
    .catch(error => {
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kepler1359 profile image
Kepler1359 • Edited on

Now, I understand that you're able to use arrow functions in more diverse ways, but after looking at the code I had trouble with I realize that pranay rauthu used a "hidden if-statement" how does one use the ampersand(&) to make a conditional, and to see if arg === some-value, and print a value based on what the client set arg equal to.

If someone has a response to my question, please point me to some resource so I can deepen my knowledge on javascript