JavaScript Logical Operators

|| (OR)

• console.log(false || false) //false
• console.log(false || true) //true
• console.log(true || false) //true
• console.log(true || true) //true
• console.log(true || true || true) //true

let score=Number(prompt("Enter Score:"));
if(score==50||score==100){
    alert("Congratulation")
}

let cDeveloper="";
let javaDeveloper="";
console.log(cDeveloper ||javaDeveloper ||"Brendan Eich"); // Brendan Eich

let cDeveloper="Dennis Ritchie";
let javaDeveloper="James Gosling";
console.log(cDeveloper ||javaDeveloper ||"Brendan Eich"); // Dennis Ritchie Eich

---

! (NOT) - Reverse the result

• console.log(!false) //true
• console.log(!true) //false
• console.log(!!true) //true

---

?? (Nullish coalescing)

Return the first argument, if it is not null or undefined, otherwise return the second argument.

let ebook="";
console.log(ebook ?? "JavaScript Cookbook"); //JavaScript Cookbook

let ebook="JavaScript Recipes";
console.log(ebook ?? "JavaScript Cookbook"); //JavaScript Recipes

&& (AND)

• console.log(false && false) //false
• console.log(false && true) //false
• console.log(true && false) //false
• console.log(true && true) //true
• console.log(true && true && true) //true

let age=Number(prompt("Enter Age:"));
if(age>=15 && age>=24){
    alert("Youth Age Group")
}

let cDeveloper="";
let javaDeveloper="";
console.log(cDeveloper &&javaDeveloper &&"Brendan Eich"); // blank

let cDeveloper="Dennis Ritchie";
let javaDeveloper="James Gosling";
console.log( cDeveloper &&javaDeveloper &&"Brendan Eich"); // Brendan Eich

---