7 posts tagged with "interview"

1. How do you decide when to run useLayoutEffect?

   Ans: useLayoutEffect is a version of useEffect that fires before the browser repaints the screen.

   • Measuring layout before the browser repaints the screen.
   • Blocks the browser from repainting.

2. The execution order of useEffect and useLayoutEffect.

   Feature	useEffect	useLayoutEffect
   Execution Timing	Runs after the render is committed to the screen. This means it runs after the browser has painted changes to the screen.	Runs synchronously after all DOM mutations. This means it runs before the browser has a chance to paint, making it suitable for reading layout from the DOM and synchronously re-rendering.
   Use Cases	Most side effects (data fetching, subscriptions)	DOM manipulation, measuring elements, critical layout updates
   Performance	Generally better performance due to async nature	Can impact performance if used excessively, as it blocks the browser from repainting

1. What are JS primitive data types?
   1. What's the use of Symbol?
   2. Have you used BigInt?
2. Tell me about prototype chain.
3. How do you implement a virtualized list? solution
4. Map vs plain object? MDN solution
5. flexbox
6. How to narrow a variable's type in typescript?

• React virtual dom
• Diff algorithm
• git merge vs git rebase

1. Browser cache. - cookie.
2. Breadth-First Traversal and Depth First Traversal.
3. script tag. async and defer.
4. React Hook

var obj = {
  a: 1,
  foo: function (b) {
    b = b || this.a;
    return function (c) {
      console.log(this.a);
      console.log(b);
      console.log(c);
    };
  },
};

var a = 2;
var obj2 = { a: 3 };

obj.foo(a).call(obj2, 1);
obj.foo.call(obj2)(1);

1. Promise.all() vs Promise.race().
2. Use CSS to draw a triangle.
3. HTTP1.1 vs HTTP2.0
4. DNS
5. flex: 0 auto or flex: 1 auto
6. CSS position.
7. What happen after typing www.google.com in your Browser?
8. prototype.
9. Determine if an object is an Array.

When we are discussing about my projects. The interviewer asked the following questions:

1. How do you achieve infinite play effect in a carousel?
2. Use JS to achieve #id's scroll to element effect.
3. CSS animation.

After done talking my projects, I was asked a few questions about Promise, linked list, and heap sort, insertion sort.

• React fiber
• Event loop
  • why do we need two task queues? (priority)
• CSS animation vs. JS animation
• Some questions about CSS animation
• How Does JS Achieve Async?
• CSS Grid
• CSS Float
• Depth First Search
• Prototype