A comprehensive suite of utility methods for working with JavaScript iterables and async iterables.
iter-tools is a JavaScript library that provides a comprehensive suite of utility methods for working with iterables and async iterables. It solves the problem of manipulating sequences of values lazily and abstractly, freeing developers from concerns about data storage and mutation while offering performance benefits in garbage-collected environments.
JavaScript developers building applications that benefit from lazy evaluation, functional programming patterns, or working with complex data sequences, particularly in web applications where responsiveness is critical.
Developers choose iter-tools for its full parity between sync and async iterables, currying support for functional composition, robust TypeScript integration, and performance optimizations like tree-shaking and low-level `__` methods, all without runtime dependencies.
The iterable toolbox
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Methods are curried, enabling functional composition with pipe or compose for cleaner, more abstract code pipelines, as highlighted in the README's features.
Guarantees identical API coverage for both synchronous and asynchronous iterables, implemented separately for performance, ensuring consistency across data types.
Treats null and undefined as empty iterables by default, eliminating a class of null pointer errors in methods like filter or map, as noted in the key features.
Offers low-level __ methods for critical loops and supports tree-shaking with dual module support, reducing bundle size in modern web applications.
Includes and validates type definitions for TypeScript >3.8.2 on every PR, providing robust type safety and developer tooling.
Admits that methods like groupBy are not provided, as they only make sense with arrays, limiting use in projects heavily reliant on array-specific operations.
__ methods lack currying, null safety, and type definitions, making them less ergonomic for general use despite performance gains, and they return singleton iterators.
Methods such as arrayFrom or cycle can hang with infinite inputs, with no current warning system, posing a pitfall for developers unaware of this limitation.
Requires manual loading of core-js for environments without native Symbol.iterator support, adding extra configuration and potential runtime overhead.