what-is-the-truth.md

What is the Truth? 🤥

Home / What is the Truth? 🤥

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Contents ✨

➡ Truthy and Falsy

➡ Why Truthy & Falsy

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Truthy and Falsy

In JavaScript when a value is encountered in a Boolean context - such as an if statement - it will be coerced into a boolean. If the result is true then the value is truthy and vice versa.

Example:

// Truthy
> true; // true
> !! "hello"; // true
> !! -1; // true (All numbers except 0 are true)
> !! []; // true
> !! {}; // true
> !! function demo() {} // true

// Falsy
> false; // false
> !! null; // false
> !! undefined; // false
> !! 0; // false
> !! ""; // false

If you’re unsure about a value, you can convert it using the logical "!" NOT operator twice "!!".

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Why Truthy & Falsy

Knowing what does a variable return helps the programmer to control the flow of the program.

function unicorns(name) {
  const unicon = name;
  if (unicorn) {
    return "Unicorns Exists!";
  } else {
    return "Unicorns Don't Exists!";
  }
}

console.log(unicorns("🦄")); // Unicorns Exists!
console.log(unicorns()); // Unicorns Don't Exists

Above is a simple demostration about how the control can be handled using Truthy and Falsy.

Lets recapitulate 📝:

➡ Empty primitive values are false, where as objects is true.

➡ Truthy and Falsy are used to control the flow of the program.

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See also:

⚫ Promises 🤝 and Async/Await 🤯 Read ▶
⚫ Hoisting 🏴‍☠️ ? ...is this a Ship? 🤨 Read ▶
⚫ Event Loop. 🔁 😵 Read ▶