let string = "The cat is black"

How to find the index/position of "cat" in the string

(a)  

let string = "The black cat is black"

How to find the LAST index/position of "black" in the string

(a)  

let string = "Milk, chocolate, cookies"

How to extract a new string "chocolate, cookies" from the first string

(a)  

let string = "Milk, chocolate, cookies"

How to replace "chocolate" with "banana"?

(a)  

let string = "Milk, chocolate, cookies"

How to figure out what character is on the 3rd position of the string?

(a)  

let string = "Milk, chocolate, cookies"

How to convert the string to upper case?

(a)  

let string = "Milk, chocolate, cookies"

How to convert the string to lower case?

(a)  

let string = " Hello World! "

How to trim the whitespaces around "Hello World!" ?

(a)  

let string = "a, b, c, 1, 2, 3"

How to convert this string into the array: ["a", "b", "c", "1", "2", "3"]?

(a)