JSON, forms and uploads

Use a parser appropriate to the body format.

UnderstandStudy an examplePractise

Understand the concept

JSON, URL-encoded forms and multipart bodies need different parsers. Multipart boundaries separate parts. When sending FormData, let the browser generate Content-Type including its boundary; manually setting only multipart/form-data can break parsing.

Extensions and submitted media types do not prove file contents. Enforce size, part counts, allowed formats, content checks and safe storage names. Do not place executable uploads in a served directory. Mismatched proxy/API limits can produce 413 failures.

Streaming reduces memory usage but does not justify unlimited inputs. Base64 inside JSON adds overhead to binary uploads. Use placeholders rather than real credentials in examples and logs.

WHEN TO USE IT

Build reliable blog-image and CV uploads.

COMMON PITFALL

Manually setting multipart Content-Type without a boundary.

01 / PRACTICE

One topic. Three levels of depth.

HTTP / illustrative example

Content-Type: application/json

{"title":"HTTP"}

A JSON body.

This page does not send requests to external servers. Messages are readable HTTP/1.1 illustrations, not HTTP/2 or HTTP/3 wire dumps. example.test is reserved for examples. Run commands and JavaScript only in your own test environment; never publish real tokens or cookies.

02 / YOUR TURN

Try it yourself first.

Can you assume a .png filename proves image content?

Show the solution and explanation

Worked solution

Extension ≠ verified content

No; validate content and storage independently.

RasimAtaberkŞahin

Understand the concept

One topic. Three levels of depth.

Try it yourself first.