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Learning TypeScript 2.x - Second Edition
book

Learning TypeScript 2.x - Second Edition

by Remo H. Jansen
April 2018
Beginner content levelBeginner
536 pages
13h 21m
English
Packt Publishing
Content preview from Learning TypeScript 2.x - Second Edition

Iterables

An iterator is a behavioral design pattern that is common in OOP. An iterator is an object that implements an interface such as the following one:

interface Iterator<T> { 
    next(value?: any): IteratorResult<T>; 
    return?(value?: any): IteratorResult<T>; 
    throw?(e?: any): IteratorResult<T>; 
} 

The preceding interface allows us to retrieve the items available in a collection. The iterator result allows us to know if we have reached the last item in the collection and to access the values in the collection:

interface IteratorResult<T> { 
    done: boolean; 
    value: T; 
} 

We can create custom iterators by implementing the IterableIterator interface. We will need to implement the next method and a method named Symbol.iterator:

class Fib implements ...
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Publisher Resources

ISBN: 9781788391474Supplemental Content