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Omi
Omi

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Will it catch?🤯

#promise #async #errors

Was just recovering from last Node.js blocking non-blocking stuff, I come to another JS injury called error-handling with promises.

This injury was again caused to me by not being able to distinguish between blocking and non-blocking code.

The below question is from javascript.info website.

What do you think? Will the .catch trigger? Explain your answer.

new Promise(function (resolve, reject) { setTimeout(() => { throw new Error("Whoops!"); }, 1000); }).catch(console.error);
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The hint: Look at the code like this:

new Promise(function (resolve, reject) // try { { setTimeout(() => { throw new Error("Whoops!"); }, 1000); }) //} catch { .catch(console.error); // }
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Comment down your answer below!

Top comments (2)

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deep_gandhi_4070895b20965 profile image
Deep Gandhi •

I thought the compiler would catch it, but when I ran it, the result differed from my expectation. Maybe it's because the error is in a different scope inside setTimeout? 🤔

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ompals profile image
Omi •

The main thread execution looks something like this:

new Promise(function (resolve, reject) try { // Register a setTimeout I/O } catch(e) { console.error(e.message); } // After 1 second throw new Error("Whoops!");
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The throw error statement will hang outside try...catch guards when defined in a callback of an async operation.