REST + fetch()

HTTP methods

fetch — GET

fetch("https://api.example.com/data")
    .then(res => res.json())
    .then(data => {
        console.log(data);
    })
    .catch(err => console.log("Error:", err));

fetch — POST

fetch("https://api.example.com/data", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ name: "Ali", age: 25 })
})
    .then(res => res.json())
    .then(data => alert("Saved!"));

Line-by-line meaning

• fetch(url) — make the HTTP request
• .then(res => res.json()) — parse response body as JSON
• .then(data => {...}) — use the actual data object
• JSON.stringify(obj) — convert JS object to a string for the server
• headers: {"Content-Type":"application/json"} — tells server body is JSON

Status codes

200 OK · 201 Created · 400 Bad request · 404 Not found · 500 Server error