JAVASCRIPT

?? in javascript

"??" is called Nullish coalescing operator.
return the right hand side of operator if left hand side is null or undefined.
For example.
const foo = null ?? 'default string';
console.log(foo);
// expected output: "default string" because left hand side is null

const baz = 0 ?? 42;
console.log(baz);
// expected output: 0 . because 0 is not null or undefined.

... in javascript

// The `...` operator breaks down an array to individual arguments.
// For example lets create an array,
let array = [1, 2, 3];

// And a function that will return a sum of 3 values.
function sum(x, y, z) {
	return(x + y + z);
}

// The `sum` function doesn't accept an array as a single argument,
// so a solution for this would be calling it individual indexes in the array:
sum(array[0], array[1], array[2]);

// Or we can just do:
sum(...array)
// does the same thing

?. in javascript

The optional chaining operator (?.) enables you to read the value of a
property located deep within a chain of connected objects without having
to check that each reference in the chain is valid.

... in javascript

let array = [...value]