replace instance of character in typescript code example

Example 1: replace string in typescript

var re = /apples/gi; 
var str = "Apples are round, and apples are juicy.";
var newstr = str.replace(re, "oranges"); 
console.log(newstr)

Example 2: string one char change in typescript

let hello:string = "Hello World";
console.log(hello.replaceAt(2, "!!")); // Should display He!!o World