inute 中的 JavaScript

let name = "john";
const age = 30;
var isstudent = true;

function greet() {
  console.log("hello, world!");
}

greet(); // output: hello, world!

let time = 20;
if (time < 12) {
  console.log("good morning");
} else if (time < 18) {
  console.log("good afternoon");
} else {
  console.log("good evening");
}

for (let i = 0; i < 5; i++) {
  console.log(i); // output: 0 1 2 3 4
}

<button onclick="sayhello()">click me</button>
<script>
  function sayhello() {
    alert("hello!");
  }
</script>

<p id="demo">this is a paragraph.</p>
<button onclick="changetext()">change text</button>
<script>
  function changetext() {
    document.getelementbyid("demo").innerhtml = "text changed!";
  }
</script>

let fruits = ["apple", "banana", "cherry"];
console.log(fruits[0]); // output: apple

let person = {
  firstname: "john",
  lastname: "doe",
  age: 30
};
console.log(person.firstname); // output: john

const add = (a, b) => a + b;
console.log(add(2, 3)); // output: 5

let name = "john";
console.log(`hello, ${name}!`); // output: hello, john!

let person = { firstName: "John", lastName: "Doe" };
let { firstName, lastName } = person;
console.log(firstName); // Output: John