dict

A dict (dictionary) stores key-value pairs. It's Python's equivalent of a JS object, and you'll use it everywhere — request bodies, JSON responses, database rows, config values.

JavaScript:

const user = {
  id: 1,
  name: 'John',
  email: 'john@example.com',
};

console.log(user.name);

user.age = 25;

Python:

user = {
    "id": 1,
    "name": "John",
    "email": "john@example.com"
}

print(user["name"])

user["age"] = 25

Key differences from a JS object

Python only uses bracket access — there's no dot notation.

user["name"]   # ✅ works
user.name      # ❌ AttributeError

JS lets you use user.name or user["name"] interchangeably. Python dicts only support the bracket form.

Adding a new key works the same way in both languages — just assign to a key that doesn't exist yet:

user["age"] = 25

Accessing a missing key behaves differently:

user["phone"]
# ❌ KeyError: 'phone'

In JS, user.phone would just quietly give you undefined. Python raises an error instead — which is exactly why the .get() method (covered on the next page) exists.