spawn for streaming processes in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the spawn function in Node.js do?

It starts a new process to run a command or script, allowing you to stream data to and from that process without waiting for it to finish.

intermediate

How does spawn differ from exec in Node.js?

spawn streams data in chunks and is better for large outputs, while exec buffers all output and returns it at once, which can cause memory issues with big data.

beginner

What are the main streams available on a spawn child process?

The main streams are stdout for standard output, stderr for error output, and stdin for input to the process.

beginner

Why is streaming output from spawn useful in real-life applications?

It lets you process data as it arrives, like showing progress or handling large files without waiting for the whole task to finish, making apps faster and more responsive.

intermediate

How can you handle errors when using spawn?

Listen to the error event on the spawned process and also check the stderr stream for error messages.

Which Node.js module provides the spawn function?

A child_process

B fs

C http

D stream

The spawn function is part of the child_process module used to create new processes.

What type of data does spawn return for output streams?

A Buffered string after process ends

B Only error messages

C No output at all

D Streamed chunks of data as they arrive

spawn streams output data in chunks, allowing real-time processing.

Which event should you listen to for errors when using spawn?

A close

B error

C data

D exit

The error event signals problems starting or running the child process.

Why might you choose spawn over exec?

A To handle large output streams efficiently

B To run commands synchronously

C To get output only after process ends

D To avoid using streams

spawn streams output, making it better for large data than exec, which buffers all output.

Which stream do you write to if you want to send input to a spawned process?

A stdout

B stderr

C stdin

D exit

stdin is the writable stream to send input to the child process.

Explain how you would use spawn to run a command and process its output as it streams.

Think about how streams let you handle data bit by bit.

Describe the differences between spawn and exec and when to use each.

Consider memory use and output size.