how to return a character as another character in js code example

Example 1: javascript get first character of string

var str="Hello Folks!"
var firstStringChar = str.charAt(0); //H

Example 2: string charat javascript

let str = new String("This is string"); 
console.log("str.charAt(0) is:" + str.charAt(0)); 
console.log("str.charAt(1) is:" + str.charAt(1)); 
console.log("str.charAt(2) is:" + str.charAt(2)); 
console.log("str.charAt(3) is:" + str.charAt(3)); 
console.log("str.charAt(4) is:" + str.charAt(4)); 
console.log("str.charAt(5) is:" + str.charAt(5));

output:

str.charAt(0) is:T 
str.charAt(1) is:h 
str.charAt(2) is:i 
str.charAt(3) is:s 
str.charAt(4) is:
str.charAt(5) is:i