use substring in react code example

Example 1: js substring

// the substring method returns a string out of another string

const str = 'Mozilla';

console.log(str.substring(1, 3));
// expected output: "oz"

console.log(str.substring(2));
// expected output: "zilla"

Example 2: reactjs cut part of string

var str = "Hello world!";

var res = str.substring(1, 4);

// res value is "ell"