let result = "// for loop
";
for (let i = 1; i <= 5; i++) result += "i = " + i + "
";
result += "
// for...of (array)
";
const langs = ["HTML", "CSS", "JS"];
for (const lang of langs) result += lang + " ";
result += "
// for...in (object)
";
const user = { name: "Ali", age: 25, level: 5 };
for (const key in user) result += key + ": " + user[key] + "
";
result += "
// while + break
";
let n = 0;
while (true) { n++; if (n > 3) break; result += n + " "; }
document.getElementById('output').innerHTML = result;