What’s the Python Equivalent of JavaScript Promises?

In JavaScript, a Promise is a fundamental abstraction for handling asynchronous operations. It allows you to run tasks asynchronously and handle their eventual completion (or failure) using .then(), .catch(), and async/await syntax.

Python provides similar asynchronous capabilities, but its implementation is more native to the language. Instead of Promise, Python uses coroutines and the asyncio module, with the async/await syntax offering behavior closely analogous to JavaScript Promise.

Python Equivalent: asyncio.Future or async/await

Python defines asynchronous operations using async def, which returns coroutine objects that can be awaited. This is functionally similar to how Promise works in JavaScript. Let’s understand with a Python code example

import asyncio
async def get_data():
    await asyncio.sleep(1)  # Simulates an async I/O operation
    return "data received"
async def main():
    data = await get_data()
    print(data)
asyncio.run(main())

Key Concepts

• async def: Declares an asynchronous function (coroutine).
• await: Waits for the result of another coroutine or asynchronous task.
• asyncio.run(): Runs the top-level entry point for asynchronous programs.

Final Notes

While both JavaScript and Python support asynchronous programming, Python's implementation via async/await and asyncio is more tightly integrated into the language. There is no separate Promise object in Python, but the behavior and usage are conceptually similar through coroutines and futures.