#24 What are headers in fetch()? Explain content-type.

Headers in the fetch() API are key-value pairs sent along with HTTP requests or responses to provide metadata like content format, authorization, etc.

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🔹 Example of Headers in fetch():

fetch('https://api.example.com/data', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',  // Tells server the format of body
    'Authorization': 'Bearer your-token-here' // Used for auth
  },
  body: JSON.stringify({ name: 'Teekam' })
});

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🔹 What is Content-Type?

Content-Type tells the server what format the request body is in so it knows how to parse it.

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🔸 Common Content-Type Values:

• 'application/json' → Sending JSON data
• 'application/x-www-form-urlencoded' → Form data in URL-encoded format
• 'multipart/form-data' → For file uploads (used with FormData)

---

🔹 Example: JSON Request

fetch('/api/login', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({ email: 'test@test.com', password: '123456' })
});

✅ This tells the server: “I’m sending JSON, please parse it accordingly.”