use proper ES6 syntax including using let/const properly.

do not use Regular Expressions (Regex)

HINT: Refer to Mozilla Developer Docs as needed

Problem 7 -

• Write a function called letterMap
• This function takes one argument which is an array
• This function creates and object where the lowercase letter is the key and the uppercase letter is the value
• The function should created the object so that is always in alphabetical order
• This function returns the object

Example:

letterMap(['Z', 'a', 'b', 'y', 'x', 'c'])

output: { a: 'A', b: 'B', c: 'C', x: 'X', y: 'Y', z: 'Z' }

THIS IS IN JAVASCRIPT PLEASE