Double_Char.js

/* DESCRIPTION:
Given a string, you have to return a string in which each character (case-sensitive) is repeated once.

Examples (Input -> Output):
* "String"      -> "SSttrriinngg"
* "Hello World" -> "HHeelllloo  WWoorrlldd"
* "1234!_ "     -> "11223344!!__  " */


/* ------------------------------------------------------------------------------------------- */

const doubleChar = (str) => {
    return  str.split('').map(elm => elm.repeat(2)).join('')
}

console.log(doubleChar("String"))