Can someone explain step by step, what is happening in this JavaScript code?

Question

let acc=1234567891;
let last= +acc.toString()[acc.toString().length-1];

switch(last){ // 1,6
case 1: case 6: console.log("eligible"); break
default : console.log("not eligible");
}

Answer 1

since acc is a number so acc.toString() will convert to string (as you cannot access a value from a number using index so you have to convert number in string)

now the length of converted string is 10

So +acc.toString()[10 - 1];

+acc.toString()[9]
+1 //here 1 is a string because of acc.toString() but there is + so +1 will be a number

So last = 1

Just try this

console.log(typeof (acc.toString()[acc.toString().length - 1]))

console.log(typeof +(acc.toString()[acc.toString().length - 1]))