why is start js startswith code example

Example 1: js startswith

var str = "Hello world, welcome to the universe.";
var n = str.startsWith("Hello");

Example 2: js startswith

const str1 = 'Saturday night plans';

console.log(str1.startsWith('Sat'));
// expected output: true

console.log(str1.startsWith('Sat', 3));
// expected output: false