Exploring TypeScript with personalized iterators

Question

Exploring TypeScript with personalized iterators

Can anyone help me figure out how to create an iterator for my array in TypeScript without encountering a transpilation error? Is it possible using generics or some other method?

let array4 = [10, 20, 30];

array4[Symbol.iterator] = function () {
  let i = 0;
  return {
    next: function() {
      i++;
      return {
        value: i < 4 ? array4[i - 1] : undefined,
        done: i >= 4 ? true : false
      };
    }
  };
};

let it4 = array4[Symbol.iterator]();

console.log(it4.next());
console.log(it4.next());
console.log(it4.next());
console.log(it4.next());

typescript ecmascript-6 iterator

Answer 1

Answer №1

Another approach to this problem is to use a custom generator function. Here's a simple example:

function* customIterator(data: any[]) {
  for (var i = 0; i < data.length; i++) {
    yield data[i];
  }
}

let array5 = [5, 10, 15];
var it5 = customIterator(array5);
console.log(it5.next()); // { value: 5, done: false }
console.log(it5.next()); // { value: 10, done: false }
console.log(it5.next()); // { value: 15, done: false }
console.log(it5.next()); // { value: undefined, done: true }

I hope you find this solution useful.

Answer 2

Another approach to this problem is to use a custom generator function. Here's a simple example:

function* customIterator(data: any[]) {
  for (var i = 0; i < data.length; i++) {
    yield data[i];
  }
}

let array5 = [5, 10, 15];
var it5 = customIterator(array5);
console.log(it5.next()); // { value: 5, done: false }
console.log(it5.next()); // { value: 10, done: false }
console.log(it5.next()); // { value: 15, done: false }
console.log(it5.next()); // { value: undefined, done: true }

I hope you find this solution useful.

Answer 3

Answer №2

For example:

myArray[Symbol.iterator] = function* () {
    let index = 0;
    while (index < 4) {
        index++;
        yield myArray[index - 1];
    }
};

If you prefer, you can achieve the same result without using a generator function by ensuring the correct signature of IterableIterator<T>. Feel free to ask for assistance if needed.

Answer 4

For example:

myArray[Symbol.iterator] = function* () {
    let index = 0;
    while (index < 4) {
        index++;
        yield myArray[index - 1];
    }
};

If you prefer, you can achieve the same result without using a generator function by ensuring the correct signature of IterableIterator<T>. Feel free to ask for assistance if needed.

Answer 5

Answer №3

If you're looking for a library to simplify your tasks, consider checking out this one: https://github.com/labs42io/itiriri. Once you have it installed, you can easily perform operations like:

q = query([10,20,30]);
q.take(2).toArray(); // [10,20]
q.filter(e => e > 10).toArray(); // [20,30]

You'll find that this library makes your coding much more efficient.

Answer 6

If you're looking for a library to simplify your tasks, consider checking out this one: https://github.com/labs42io/itiriri. Once you have it installed, you can easily perform operations like:

q = query([10,20,30]);
q.take(2).toArray(); // [10,20]
q.filter(e => e > 10).toArray(); // [20,30]

You'll find that this library makes your coding much more efficient.

Exploring TypeScript with personalized iterators

Answer №1

Answer №2

Answer №3

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