Question 1

What is the difference between PUT and PATCH?

Accepted Answer

PUT replaces a resource entirely with the representation you send. PATCH applies a partial modification. The distinction determines what happens to fields you do not mention, and that is where most confusion and most bugs live.

With a correct PUT, omitting a field means setting it to empty or default, because you are declaring the complete new state. Sending only the fields you want to change would clear everything else. In practice many APIs implement PUT as though it were PATCH, ignoring absent fields, which works until someone reads the specification and expects replacement semantics.

PATCH sends only what should change, and unmentioned fields are left alone. That is the behaviour most applications actually want for an edit form.

Idempotency differs too. PUT is idempotent by definition: sending the same complete representation repeatedly lands on the same state. PATCH is not necessarily, because a patch can be expressed as an operation such as incrementing a counter, which compounds when repeated. A patch that simply sets fields is idempotent in practice.

There is a genuine ambiguity PATCH does not resolve on its own: distinguishing a field omitted because it should not change from a field explicitly set to empty. If your representation allows null values, those two cases look identical in JSON unless you decide a convention. Formats such as JSON Merge Patch define one, treating null as delete, at the cost of being unable to set a field to null.

The pragmatic advice is to pick one, document what happens to omitted fields, and be consistent. An API where the answer varies by endpoint is the worst outcome.

Question 2

What is API versioning, and how do you avoid breaking clients?

Accepted Answer

Managing change in an interface other people depend on — where the governing constraint is that once an API is published, you no longer control when consumers update, and in many cases they never

Question 3

What is semantic versioning and what does the caret mean?

Accepted Answer

Semantic versioning encodes intent in a three-part number. The major version increments on a breaking change, the minor on a backwards-compatible addition, and the patch on a backwards-compatible

Question 4

What is idempotency and why does it matter for APIs?

Accepted Answer

An operation is idempotent when performing it more than once has the same effect as performing it once. Setting a value to ten is idempotent; adding ten is not. The property matters because networks

Question 5

What is the difference between a linter and a formatter?

Accepted Answer

A formatter changes how code looks. A linter analyses what code does and flags problems. They are complementary, and confusing them leads to teams configuring one to do the other's job badly. A

Question 6

What is dependency injection and why does it help?

Accepted Answer

Dependency injection means a component receives the things it depends on from outside, rather than constructing them itself. The contrast. Without it, a class creates its own collaborators: A

Question 7

What does git stash do and when should I use it?

Accepted Answer

Stashing takes your uncommitted changes, saves them aside, and returns the working tree to a clean state matching the last commit. The changes are not lost; they are stored on a stack you can reapply

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