Next
An iterator operation that advances an iterator and returns its next value or result, with behavior on exhaustion determined by the API.
Get Programming with JavaScript Next: New features of ECMAScript 2015, 2016, and beyond
A method on a generator object that advances execution until the next yield or completion and may supply a value back into the generator.
- How it is used
- Advances generators one yield at a time and lets iterators supply values to consumers.
- How deep it goes
- Works through initial calls, yield feedback, completion results, and the iterator return contract without descending into language internals.
- Examples
- Traces yielded letters, constructs a prime-number iterator, and feeds previous outcomes into a simulation generator.
- What you can do after
- Build it from scratch as a generator or iterator that yields successive values and handles completion or feedback.
Secrets of the JavaScript Ninja, Second Edition
An iterator method that advances iteration and returns the next result; for a generator, it can also pass a value into the suspended computation.
- How it is used
- Requests generator values on demand and, when given an argument, sends data into suspended execution.
- How deep it goes
- Works through iterator result objects, suspension, completion, and passing values into yield; does not develop a general iterator implementation.
- Examples
- Uses a two-value generator, an ID counter, and a generator that receives an argument through next().
- What you can do after
- Practice/perform it: advance a generator manually, check whether it is done, and pass a value into a suspended yield.
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Python How-To
- How it is used
- Advances an iterator item by item, including when consuming a CSV header before processing data rows.
- How deep it goes
- Explains iterator advancement and `StopIteration` on exhaustion, then contrasts manual calls with exhaustion handling in `for` loops.
- Examples
- Demonstrates retrieving task-list items and consuming a CSV header before iterating over its data rows.
- What you can do after
- Apply it by retrieving iterator items manually or consuming a CSV header before looping over remaining rows.
Learn Rust in a Month of Lunches
next is the iterator method that advances iteration and returns an Option containing the next item or indicating that iteration has ended.
- How it is used
- Drives lazy iterators manually or supplies the stopping behavior used by for loops and consuming iterator methods.
- How deep it goes
- Explains repeated calls, Some and None results, laziness, and custom implementations without detailing iterator internals beyond state updates.
- Examples
- Uses a character vector, assertions, for loops, and custom iterators that alternate, repeat indefinitely, or yield library books.
- What you can do after
- Operate iterators manually, interpret Option results, and implement next for custom Iterator types.
100 Java Mistakes and How to Avoid Them
Iterator.next is the Java Iterator method that returns the next element and throws NoSuchElementException when none remains.
- How it is used
- Implements custom Collection, Map, or Iterable traversal and supports consumers beyond enhanced for loops.
- How deep it goes
- Explains call ordering, exhaustion behavior, buffering, and corrected implementations, but does not discuss iterator removal.
- Examples
- Uses numeric range iterators, Collections.min(), BufferedReader iteration, and standard stream-based iterator alternatives.
- What you can do after
- Build custom iterators that remain correct under direct next() calls, unusual call sequences, and exhaustion.
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Related concepts
- generatoruses · A generator is a language construct or computation that produces values incrementally on demand, typically suspending and resuming while preserving its state.
- iteratoruses · An iterator is an object or abstraction that provides successive values from a sequence or data source through a traversal protocol.
- yielduses · A language construct that yields control from a computation, optionally passing a value to another context, and may allow the suspended computation to continue later.
- doneproduces · done is a Boolean property of an iterator result that indicates whether the iterator has finished producing values.
- value propertyproduces · The value property is the field of an iterator result object that contains the item produced for the current iteration step.
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