????? ????? ??? JavaScript? 1995? Brendan Eich? ?? ? 10? ?? ???????. ?? ???? ? ??? ??? ?????? ???? ??? ??? ??? ?????. ??? ???? JavaScript? ?? ? ??? ???? ???? ??? ??? ??????. ??? ?? ??????? ??? ????? ???? ??? ???? ?? JavaScript ??? ???? ????.

?????? JavaScript ??? ??? ? ??? ? ?? ? ?? ???? ??? ???????. ?? ??? ?? ???? ???? ?? ??? ?? ??? ??? ???? ??? ?????.

1. ?? ??? ??? ??????

JavaScript? ?? ????? ??? ??? ??? ? ????. ?????? ??? ??? ?? ????? ??? ? ?? ??? ??? ? ???, ?? ?? ?? ??? ?????? ??? ?? ??? ??? ? ????.

var user = "Admin"; // Declared in the global scope
function setUser() {
    user = "Guest"; // Accidentally overwrites the global variable
}
setUser();
console.log(user); // "Guest" - Unintended behavior

IIFE(?? ?? ?? ???)? ???? ??? ??? ?? ?? ?? ??? ??? ?? ??? ???? ?? ??? ? ????. ??? ?? ??? ? ???? ???? ?????.

(() => {
    let user = "Admin"; // Scoped to this block
    function setUser() {
        user = "Guest";
    }
    setUser();
    console.log(user); // "Guest" - Intended behavior
})();

2. ???? ?? ??? ??

?? ??? JavaScript ??? ??? ?? ??? ????? ??? ??? ???? ???? ??? XSS(?? ??? ????) ??? ?? ?? ??? ??? ? ????.

const userInput = "<script>alert('Hacked!')</script>";
document.getElementById("output").innerHTML = userInput; // Wrong!

textContent? ????? ??? ???? ???? ?? ????? ???? ?? ??? ? ????.

const userInput = "<script>alert('Hacked!')</script>";
const sanitizedInput = userInput.replace(/</g, "<").replace(/>/g, ">");
document.getElementById("output").textContent = sanitizedInput;

3. eval()? ?? ??? ??

eval() ??? ????? ??? ??? ? ?? ??? ?????. ?? ??? ?? ??? ?? ???? ? ??? ? ????.

const userCode = "alert('Hacked!')";
eval(userCode); // Wrong!

eval()? ??? ???? ?? ??? ?? ??? ?? ??? ?? ?? ??? ??? ?????.

const userCode = "alert('Hacked!')";
// Avoid eval(); implement safer alternatives
try {
    const safeFunction = new Function(userCode); // Limited scope execution
    safeFunction();
} catch (e) {
    console.error("Execution failed:", e);
}

4. ?? ?? ??

??? ????? ?? ???? ?? ????? ?? ??? ??? ?? ????.

const fetchData = async () => {
    const response = await fetch("https://api.example.com/data");
    return response.json(); // Assuming API always returns valid JSON
};

?? ??? ???? ???? ?? ??? ?????.

const fetchData = async () => {
    try {
        const response = await fetch("https://api.example.com/data");
        if (!response.ok) throw new Error("Network response was not ok");
        return await response.json();
    } catch (error) {
        console.error("Fetch failed:", error.message);
        return null; // Graceful degradation
    }
};

5. ????? ??

??? ?? ?? ???? ??? ???. API ?? ????? ?? ?? ??? JavaScript ??? ?? ???? ?? ??? ?? ????? ??? ?? ??? ? ?? ??? ?? ?? ?????.

const API_KEY = "12345-SECRET";
fetch(`https://api.example.com/data?key=${API_KEY}`);

?? ??(.env ?? .env.local) ?? ?? ???? ???? ???? ?????? ??? ?????.

var user = "Admin"; // Declared in the global scope
function setUser() {
    user = "Guest"; // Accidentally overwrites the global variable
}
setUser();
console.log(user); // "Guest" - Unintended behavior

---

?? JavaScript ??? ???? ?? ?? ??? ????? ??? ????. ???? ??? ???? ???? ??? ???? ?? ?????. ???? ??? ???? ?? ??? ??? ???? JavaScript? ???? ???? ??? ?? ? ????.

???? JavaScript? ??? ? "? ??? ??????"?? ??? ???. ??? "?"?? ?? ??? ?????!

? ??? ??? JavaScript ??? ??????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!