Front End Developer – Interview Questions

Post by serve_yay » Tue, Jan 20, 2015, 7:23 PM UTC

jnbiche wrote: post #75

serve_yay wrote: post #64

Earlier quoted context omitted.

That's using a closure, another would be to use Function.prototype.bind (but really that's still using a closure, just putting it out of sight), can't think of any others.

>Function.prototype.bind (but really that's still using a closure, just putting it out of sight), How is `bind` still using a closure? `bind` just allows users to alter a function's execution context. However, the implementation varies according to the JS engine. Some of them may use a closure internally as a part of the process, but I don't think V8 does.

Post by evunveot » Tue, Jan 20, 2015, 7:24 PM UTC

mkoryak wrote: post #5

I really like this js question (whiteboarding): Implement function foo which takes an integer size, and returns an array of that size where each element in that array is a function that returns the index of that function in the array. Testcase: 42 === foo(1000)[42]() There are 3 different correct solutions. Discuss which solution is better, worse... etc (if they get there) (could probably be worded better, I'm not an…

    var foo = function (arr, i) {
      if (typeof arr === 'number') { 
        arr = new Array(arr);
        foo(arr, arr.length - 1);
        return arr;
      }
      if (i === -1) {
        return;
      }
      arr[i] = function () {
        return i;
      }
      foo(arr, i - 1);
    };

Post by tericho » Tue, Jan 20, 2015, 7:31 PM UTC

cozuya wrote: post #88

driverdan wrote: post #72

Earlier quoted context omitted.

How often do you use call and apply? I've been a JS developer for a long time, have written a lot of JS code, and rarely need to use call and apply. Unless you're writing all your code from scratch and not using any frameworks / util libs (which you should) you won't need them very often.

Fairly often. Since the selected DOM element is the value of this in any event handler callback, you can migrate out the function and use it for different things (i.e. validation of, say, autofill after a settimeout) and different contexts with call/apply.

Post by oceanstone » Tue, Jan 20, 2015, 7:40 PM UTC

_greim_ wrote: post #92

steakejjs wrote: post #4

This looks like a giant list of trivia that has almost no bearing on the day-to-day effectiveness of the candidate. For example, I don't have the slightest clue what the answer is to probably half of these and a lot of my job is to write javascript that gets run millions to billions of times a day. The "code questions", by contrast, were all ridiculously easy. So, would it really matter if you are hiring someone who…

> doesn't remember the difference between .call and .apply Simply getting the names mixed up and needing to look them up is one thing, but if the unfamiliarity stems from a general unfamiliarity with those methods and their respective use cases, then it would be a red flag for a "senior dev" sort of position.

    f.apply(this, arrayOfArgs); // Array

    f.call(this, arg1, arg2, arg3); // Columns