What is the Python equivalent of a Promise from JavaScript?

QASource Engineering Team | April 28, 2025

Understanding 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.

Disclaimer

This publication is for informational purposes only, and nothing contained in it should be considered legal advice. We expressly disclaim any warranty or responsibility for damages arising out of this information and encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.

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