Understanding Booleans in JavaScript
In JavaScript, Boolean is a data type that represents a truth value. It can only have one of two values: true or false. This concept is often used to answer yes-or-no questions in code.
For instance, if you want to determine whether someone is an adult or not based on their age, you would use a Boolean variable to store this information.
What is a Boolean?
The Boolean type is like a switch with two states: true or false, yes or no. It is a fundamental data type used to represent logical decisions in programming.
Example:
javascriptCopy codelet isAdult = true; // or false
Here, the variable isAdult stores a Boolean value, which tells us if the person is an adult (true) or not (false).
Checking the Type of a Boolean Variable
In JavaScript, you can use the typeof operator to check the type of a variable. For Boolean variables, the output will always be boolean.
javascriptCopy codeconsole.log(typeof isAdult); // Output: "boolean"
Key Point: Boolean variables can only hold the values true or false.
Dynamic Typing in JavaScript
One of the powerful features of JavaScript is its dynamic typing. This means you can change the type of a variable by reassigning it a new value of a different type. For instance:
javascriptCopy codelet a = 5; // Initially, 'a' is a number
a = true; // Now, 'a' is a Boolean
In the code above, the variable a starts as a number but is later reassigned as a Boolean. This is possible in JavaScript, unlike in strongly typed languages like Java or C++, where the type of a variable is fixed once declared.
Code Example
Here's a demonstration:
javascriptCopy codelet isAdult = false; // Initially set to false
console.log(isAdult); // Output: false
isAdult = true; // Value reassigned to true
console.log(isAdult); // Output: true
// Checking the type
console.log(typeof isAdult); // Output: "boolean"
// Dynamic typing
let a = 5; // Number
console.log(typeof a); // Output: "number"
a = true; // Changed to Boolean
console.log(typeof a); // Output: "boolean"