Edit in JSFiddle

var str = "Hello world, welcome to the universe.";

// startsWith() :
var res1 = str.startsWith("Hello"); // true
var res2 = str.startsWith('world', 6); // true
// endsWith();
var res3 = str.endsWith("universe."); // true
var res4 = str.endsWith("world", 11); // true

//출력
document.write("startsWith() : <br>");
document.write(res1 + "<br>");
document.write(res2 + "<br>");
document.write("<br> endsWith() : <br>");
document.write(res3 + "<br>");
document.write(res4 + "<br>");