Javascript Logical Operators

Definition of Javascript Logical Operators

var a = 5;
var b = 10;

result = (a < b) && (b > a); //result is true: both conditions are true
result = (a > b) || (b > a); //result is true: second condition is true
result = !(a < b); //result is false: negates a true condition

Importance of Javascript Logical Operators in Computer Programming

 
if (age > 18 && citizen == true) { 
   console.log("You are eligible to vote."); 
} 

Categories of Javascript Logical Operators

• Logical AND - denoted by &&
• Logical OR - denoted by ||
• Logical NOT - denoted by !

How to Use Logical Operators in Javascript

Step-by-step Guide on Using Logical Operators in Javascript

  let a = true;
  let b = false;

 
  let result = a && b;  // result is false because b is false

 
  let result = a || b;  // result is true because a is true

 
  let result = !a;  // result is false because a is true, so negation turns it to false

 
  let result = a && !b || b;  // result is true

Practical Examples of How to Use Logical Operators in Javascript

 
  let isCartFull = false;
  let isItemAvailable = true;

  if (isCartFull || !isItemAvailable) {
    console.log("Cannot add more items to the cart.");

  } else {
    console.log("Item added to the cart successfully.");
  }

 
  let age = 20; 
  let isWithinRegion = true;

  if (age >= 18 && isWithinRegion) { 
    console.log("Access granted.");

  } else {
    console.log("Access denied.");
  }

Javascript Logical And Operator

Breaking Down the Javascript Logical And Operator

  operand1 && operand2

• false
• 0 (zero)
• '' or "" (empty string)
• null
• undefined
• NaN

Use Cases of the Javascript Logical And Operator

{ isLoggedIn && 
Welcome, user!
 }

if (username !== '' && password.length >= 8) {
  console.log('User details are valid');
} else {
  console.log('User details are not valid');
}

if (person && person.age) {
  console.log(`Person is ${person.age} years old.`);
}

Exploring the JavaScript Logical Not Operator

Comprehensive Guide on the Javascript Logical Not Operator

• false
• 0
• NaN
• undefined
• null
• Empty string ("")

!!nil;  //returns false
!!"hello";  //returns true
!!3;  //returns true

Examples of Javascript Logical Not Operator in Action

  let array = [];

  if (!array.length) {
    console.log('The array is empty!');
  }

  let input = "";  // This would come from an input field

  let isButtonDisabled = !input;

  console.log(isButtonDisabled); // Would output true because input is empty

  let isUserLoggedIn = false;

  if (!isUserLoggedIn) {
    console.log('You are not logged in!');
  }

Mastering Javascript Logical Or Operator

Detailed Explanation of Javascript Logical Or Operator

  operand1 || operand2

• false
• 0 (zero)
• '' or "" (empty string)
• null
• undefined
• NaN

How to Implement the Javascript Logical Or Operator

if (role == 'Admin' || role == 'Manager') {
  console.log('You have access to the dashboard!');
}

let name = username || 'guest';

console.log(name);

if (age < 18 || age > 65 ){
  console.log('You are not eligible for the service!');
}

let result = dangerousFunction() || safeFunction();

Unpacking Javascript Logical Assignment Operators

Introduction to Javascript Logical Assignment Operators

How and When to use Javascript Logical Assignment Operators

let a = 3;
a &&= 2; // a = a && 2 -> a = 2
console.log(a); // 2

let b = 0;
b ||= 7; // b = b || 7 -> b = 7
console.log(b); // 7

let c;
c ??= 10; // c = c ?? 10 -> c = 10
console.log(c); // 10