![Alex Devero on Twitter: "Lowercase and Uppercase Map Write a function that creates an object with each (key, value) pair being the (lower case, upper case) versions of a letter, respectively. #javascript # Alex Devero on Twitter: "Lowercase and Uppercase Map Write a function that creates an object with each (key, value) pair being the (lower case, upper case) versions of a letter, respectively. #javascript #](https://pbs.twimg.com/media/Ez-g6s7WEAMJHUm.jpg:large)
Alex Devero on Twitter: "Lowercase and Uppercase Map Write a function that creates an object with each (key, value) pair being the (lower case, upper case) versions of a letter, respectively. #javascript #
![JavaScript validation with regular expression: Check whether the first character of a string is uppercase or not - w3resource JavaScript validation with regular expression: Check whether the first character of a string is uppercase or not - w3resource](https://www.w3resource.com/w3r_images/javascript-regexp-image-exercise-1.png)
JavaScript validation with regular expression: Check whether the first character of a string is uppercase or not - w3resource
![Which built-in method returns the calling string value converted to upper case in JavaScript ? - GeeksforGeeks Which built-in method returns the calling string value converted to upper case in JavaScript ? - GeeksforGeeks](https://media.geeksforgeeks.org/wp-content/uploads/20211227014601/ezgifcomgifmaker16.gif)