07_Operators(II).js

"use strict"; // using a variable without its previous declaration is treated as an error

/*---------------------------------------String operators------------------------------------------*/

let greetings = "Hi";
console.log(greetings + " " + "Alice"); // -> Hi Alice
 
let sentence = "Happy New Year ";
let newSentence = sentence + 10191;
 
console.log(newSentence); // -> Happy New Year 10191
console.log(typeof newSentence); // -> string

let sentence = "Happy New ";
sentence += "Year ";
sentence += 10191;
console.log(sentence); // -> Happy New Year 10191

/*----------------------------------------- Comparison operators----------------------------------------*/

// Identity (Strict equality) operator ===

console.log(10 === 5); // -> false
console.log(10 === 10); // -> true
console.log(10 === 10n); // -> false
console.log(10 === "10"); // -> false
console.log("10" === "10"); // -> true
console.log("Alice" === "Bob"); // -> false
console.log(0 === false); // -> false
console.log(undefined === false); // -> false

// Equlaity operator ==

console.log(10 == 5); // -> false
console.log(10 == 10); // -> true
console.log(10 == 10n); // -> true
console.log(10 == "10"); // -> true
console.log("10" == "10"); // -> true
console.log("Alice" == "Bob"); // -> false
console.log(0 == false); // -> true
console.log(undefined == false); // -> false
console.log(NaN == NaN); // -> false (if any of the operands has a NaN value (or has been converted to NaN, e.g. with undefined), the equality operator will return false.)

// Nonidentity operator !==

console.log(10 !== 5); // -> true
console.log(10 !== 10); // -> false
console.log(10 !== 10n); // -> true
console.log(10 !== "10"); // -> true
console.log("10" !== "10"); // -> false
console.log("Alice" !== "Bob"); // -> true
console.log(0 !== false); // -> true
console.log(undefined !== false); // -> true

// inequality operator !=

console.log(10 != 5); // -> true
console.log(10 != 10); // -> false
console.log(10 != 10n); // -> false
console.log(10 != "10"); // -> false
console.log("10" != "10"); // -> false
console.log("Alice" != "Bob"); // -> true
console.log(0 != false); // -> false
console.log(undefined != false); // -> true
console.log(NaN != NaN); // -> true

// <,>,<=,>= operators

console.log(10 > 100); // -> false
console.log(101 > 100); // -> true
console.log(101 > "100"); // -> true
 
console.log(101 < 100); // -> false
console.log(100n < 102); // -> true
console.log("10" < 20n); // -> true
 
console.log(101 <= 100); // -> false
console.log(10 >= 10n); // -> true
console.log("10" <=  20); // -> true

console.log("b" > "a"); // -> true
console.log("a" > "B"); // -> true
console.log("B" > "A"); // -> true
console.log("A" > "4"); // -> true
console.log("4" > "1"); // -> true
 
console.log("ab1" < "ab4"); // -> true
console.log("ab4" < "abA"); // -> true
console.log("abB" < "aba"); // -> true
console.log("aba" < "abb"); // -> true
 
console.log("ab" < "ab4"); // -> true


/*---------------------------------------Other Operators----------------------------*/

//  typeof operator

let year = 10191;
console.log(typeof year); // -> number
console.log(typeof false); // -> boolean

//  instanceof operator

let names = ["Patti", "Bob"];
let name = names[0];
console.log(names instanceof Array); // -> true
console.log(name instanceof Array); // -> false

// delete operator

let user = {
     name: "Alice",
     age: 38
};
console.log(user.age); // -> 38
delete user.age;
console.log(user.age); // -> undefined


// ternary operator

console.log(true ? "Alice" : "Bob"); // -> Alice
console.log(false ? "Alice" : "Bob"); // -> Bob

/*-----------------------------------------------Precedence------------------------------------*/

let a = 10;
let b = a + 2 * 3;
let c = a + 2  < 20 - 15;
console.log(a); // -> 10
console.log(b); // -> 16
console.log(c); // -> false

let a, b;
b = (a = (20 + 20) * 2) > (3 ** 2);
console.log(a); // -> 80
console.log(b); // -> true


let name = 1 > 2 ? "Alice" : "Bob";
console.log(name); // -> Bob