Rest parameters

Question

Hello co-sololearners, how this function is read?
function containsAll(arr) {
for (let k = 1; k < arguments.length; k++) {
let num = arguments[k];
if (arr.indexOf(num) === -1) {
return false;
}
}
return true;
}

Answer 1

Hello there Unar Arbab :))

Let's break down the code :

Whenever you make a function in javascript, a property called 'argument' is made as well. Which is an array and contains all the arguments you pass in the function!

Using a for loop you are iterating over the arguments.

if (arr.indexOf(num) === -1) is checking if the argument exists in the array called 'arr';

Let's check it :

console.log(containsAll([4,3], 3); // true

Because the array is of 3 and 4. It has all the arguments we have passed. Now if you write it like so :

console.log(containsAll([4,3], 5); // false

Because the array isn't containing the argument we have passed!

Hope this helps :))