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JavaScript Advanced: Code That Holds Up in Production
Check Yourself: How JavaScript Actually Runs
Five scenario questions on the event loop, parallel promises and cancelling. If you miss more than one, predict the output of the examples before you run them.
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Functions That Remember
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JavaScript Closures in Real Code
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this, bind and Arrow Functions: Who Is Calling
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How JavaScript Actually Runs
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The Event Loop: Microtasks, Macrotasks and Why setTimeout(0) Isn't Zero
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Running Promises in Parallel: all, allSettled, race
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Cancelling Work With AbortController
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Data That Doesn't Fit in Memory
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Iterators and Generators
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Streams in Node.js: Reading Big Files a Piece at a Time
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Catch Bugs Before You Run the Code
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JSDoc Types and // @ts-check Without Switching to TypeScript
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ESLint in a Real Project
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Ship It, Then Make It Fast
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Bundling With Vite and Publishing to npm
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Finding Slow Code With the Performance Profiler
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Memory Leaks: Event Listeners and Closures That Never Let Go
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- Final Check: JavaScript Advanced
1.
console.log("A"); setTimeout(() => console.log("B"), 0); Promise.resolve().then(() => console.log("C")); console.log("D"); What prints?
2.
A click handler runs a loop that takes 2 seconds. A setTimeout(fn, 0) was scheduled just before it. When does fn run?
3.
A dashboard loads 9 independent widgets. If one fails, the other 8 should still show. Which do you use?
4.
You need to send 5,000 API requests. What's the main risk of ids.map(send) inside Promise.all?
5.
A user types quickly in a search box, and old results sometimes replace new ones. What's the best fix?
About
Five scenario questions on the event loop, parallel promises and cancelling. If you miss more than one, predict the output of the examples before you run them.
- Duration
- 5 min
- Last update
- 08/15/2026
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