1let str = 'John Wick'
2let firstChar = str.charAt(0)
3console.log(firstChar); // "J"
1var str="123 - aaaaa"
2var num = str.slice(0,3) //num="123"
3var name= str.slice(6) //name="aaaaa"
1var str = "Hello world!";
2
3var res = str.substring(1, 4);
4
5// res value is "ell"
6