Logical Operators

#react #beginners #javascript

`&&` - 'and'

&& - means 'and' and both the left-hand side and the right-hand side operands must be 'truthy' for && to be 'truthy.'

For example, if I tell my daughter that she will receive 🍦 if she gets an 'A' on her test and cleans her room, then both of those conditions must be true for her to get 🍦.

Here's how that might look in code:

const daughter = {
  name: "Lily",
  devToUsername: "@awesomecoder123"
  mostRecentTestScore: "A",
  roomStatus: "Clean"
}

if (daughter.mostRecentTestScore === "A" && daughter.roomStatus === "Clean) {

  // This will only 'log' if BOTH CONDITIONS are 'truthy'
  console.log("🍦");
}

And, here are a couple of examples loosely referencing how this sort of thing might work in React:

&&, if the left-hand side operand is 'false-y,' then there is no reason to evaluate the right-hand side operand.

If the left-hand side operand is 'false-y,' then we shortcircuit the &&.

Using the analogy above 👆🏽, if my daughter didn't receive an "A," there isn't any reason to check her room with regards to 🍦.

`||` - 'or'

|| - means 'or' and either the left-hand side or the right-hand side operand must be 'truthy' for || to be 'truthy.'

Using the same 'daughter analogy' 👆🏽, if the deal was that she could get 🍦 if either she got that "A," or she cleaned her room...

const daughter = {
  name: "Lily",
  devToUsername: "@awesomecoder123"
  mostRecentTestScore: "A",
  roomStatus: "Dirty"
}

if (daughter.mostRecentTestScore === "A" || daughter.roomStatus === "Clean) {

  // This will only 'log' even if the 'room is dirty' b/c she got the 'A' 😃
  console.log("🍦");
}

And, here's another example showing short-circuiting of an ||. This means that if the left-hand side operand is 'truth-y,' we don't bother to look 👀 at the right-hand side operand - we short-circuit the ||.

Finally, we see one somewhat more realistic example putting things back together.