Iterator Design Pattern
Also known as Cursor
GitHub link: https://github.com/FrancescoXX/Design-Patterns-Iterator-Javascript
Behavioral Design Pattern
⚡️Recognize
We want to separate the logic of how to access data from data itself
💡Intent
Provide a way to access the elements of an aggregate object sequentially, without exposing its representation
🔧 Apply when
We want give a way to access elements in such a way that it does not expose its internal structure;
The Iterator takes the responsibility for access and manipulation of the data structure
✅Pro
- We can define different iterators for different ways of manipulating a data structure
- Clients can use an iterator to access data without knowing the representation
🏆 Great for
Decoupling algorithms from containers
/** Iterator Design Pattern
* Behavioral Pattern
*/
/**
* @function hasNext returns true/false, depending
* if the iterator has other elements in the collection
* @function next returns the next available element in the collection
*/
class Iterator {
constructor(items) {
this.items = items; //The collection to iterate to
this.index = 0; //Starting index
}
hasNext = () => this.index < this.items.length; //Returns TRUE if there's another element, FALSE otherwise
next = () => this.items[this.index++]; //Rule for next element
}
// MAIN
//Define a collection
const animals = ["dog", "cat", "bird", "tiger", "lion"];
//Define an Iterator
const iterator = new Iterator(animals);
//Iterate over each Element
while (iterator.hasNext()) {
console.log("[", iterator.index, "] :", iterator.next());
}
// [ 0 ] : dog
// [ 1 ] : cat
// [ 2 ] : bird
// [ 3 ] : tiger
// [ 4 ] : lion
GitHub link: https://github.com/FrancescoXX/Design-Patterns-Iterator-Javascript
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