Hi everyone
I just started learning Node.js just a few hours ago, and I'm really confused (wanted to cry too). Could someone help me clarify a few things?
After I initialized a Node.js project, I see the following in package.json:
"type": "commonjs"
Then I run this code:
console.log('sync');
process.nextTick(() => console.log('nextTick'));
Promise.resolve().then(() => console.log('promise'));
The output is:
sync
nextTick
promise
Then I installed TypeScript and executed the same code again, but in a .ts file. This time, the output is:
sync
promise
nextTick
Interestingly, I get the same output when I set "type": "module" in package.json.
So I asked ChatGPT:
1. Does the TypeScript compiler change the execution order to behave like an ES module?
ChatGPT answered:
"Your tsx example produced ESM-style ordering, but you shouldn't assume every tsx file or situation will behave the same way."
Now I'm even more confused! Could someone help me clarify this?
ChatGPT's answer seems that the output when using TypeScript with CommonJS does not necessarily match the output of either CommonJS or ESM....
I also have a few related questions about the Node.js event loop:
2. As far as I know, the Node.js event loop has several phases, including:
1. Timers (setTimeout callback)
2. Poll (I/O-related callbacks, such as reading files or receiving network data)
3. Check (setImmediate callback)
Is this correct? If so, which phase runs first?
3. Are Promise callbacks handled separately from the Node.js event loop? Is the following execution sequence correct?
1. Drain the process.nextTick() queue.
2. Drain the Promise microtask queue.
3. Execute the next event loop callback (setTimeout, readFile, setImmediate, etc.)
4. Back to 1