javascript ... operator

//The OR operator in Javascript is 2 verticals lines: ||

var a = true;
var b = false;

if(a || b) {
	//one of them is true, code inside this block will be executed
}

let a = { a: 0, b: 1 };
let b = { b: 2, c: 3 };
let c = { ...a, ...b };

console.log(c);

output -> {a: 0, b: 2, c: 3}

Operator	Example	Same As
=	x = y	x = y
+=	x += y	x = x + y
-=	x -= y	x = x - y
*=	x *= y	x = x * y
/=	x /= y	x = x / y
%=	x %= y	x = x % y
**=	x **= y	x = x ** y

//The operator ... is part of the array destructuring.
//It's used to extract info from arrays to single variables.
//The operator ... means "the rest of the array".
var [head, ...tail] = ["Hello", "I" , "am", "Sarah"];
console.log(head);//"Hello"
console.log(tail);//["I", "am", "Sarah"]

//It can be used to pass an array as a list of function arguments
let a = [2,3,4];
Math.max(a) //--> NaN
Math.max(...a) //--> 4

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var a = fruits.indexOf("Banana");
var b = !a;
var c = !!a;
console.log('a:',a);
console.log('b:',b);
console.log('c:',c);

const age = 20;

console.log(`I am ${age} years old.`); // not my real age

var x = 5;         // assign the value 5 to x
var y = 2;         // assign the value 2 to y
var z = x + y;     // assign the value 7 to z (5 + 2)

/* JavaScript shorthand -=
-= is shorthand to subtract something from a
variable and store the result as that same variable.
*/

// The standard syntax:
var myVar = 5; 
console.log(myVar) // 5
var myVar = myVar - 3;
console.log(myVar) // 2

// The shorthand:
var myVar = 5;
console.log(myVar) // 5
var myVar -= 3;
console.log(myVar) // 2

x = x || 1