Factory

As explained in Build a Frontend Web Framework (From Scratch)

A function that creates and returns objects or other constructed values according to a defined creation procedure.

A factory function creates component instances with custom state, rendering, and behavior, avoiding a single application-wide state object and reducer collection. section 9.0

A component factory organizes creation around a few responsibilities:

• Create each component's state when the component is instantiated. section 9.4
• Provide a render function and methods, including updateState(), for changing state. section 9.4
• Patch the component's DOM subtree when its state changes instead of rerendering the entire application. section 9.0 section 9.4
• Bind render functions and event handlers explicitly so this refers to the component instance. section 9.4

A stateful component instance

Instead of passing global state, reducers, and a root component into createApp(), the newer architecture can receive only a root component. That component is created through a factory, owns its state, renders its view, and patches its DOM subtree after updateState() runs. section 9.0 section 9.4

Figure 9.2 The new version of the framework’s application instance requires only the root component.

Shows the architectural shift from an application requiring global state and reducers to one requiring only a root component. section 9.0

How Build a Frontend Web Framework (From Scratch) covers it

How deep it goes

Explains instantiation, state updates, view patching, and method binding, but does not provide production-level implementation details.

Examples

Uses a root component, component instances, local state, updateState(), render functions, and component DOM subtrees.

What it assumes

Assumes familiarity with stateless components, application state, reducers, the DOM, and reconciliation.

What you can do after

Build it from scratch by defining component state, rendering, updateState(), lifecycle behavior, and bound event handlers.

How it connects

Connects factories with stateful components, pure functions, reducers, lifecycle, render functions, event handlers, and DOM reconciliation.

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Also explained in

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  Unit Testing Principles, Practices, and PatternsA factory is a creation abstraction that constructs domain objects from input data while encapsulating instantiation or reconstruction logic.
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  Infrastructure as Code, Patterns and Practices: With examples in Python and TerraformA factory module is a reusable infrastructure module that generates standardized infrastructure resources from inputs and default configuration values.
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  The Art of Unit Testing 3eA factory function is a function that creates and returns an object, value, or configured function.
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  Software Design for Python ProgrammersA factory function is a function that encapsulates creating and returning objects, often selecting among subclass types based on an input value.
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  Object-Oriented Software Design in C++A class responsible for creating and selecting instances of other classes while hiding construction details from clients.
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  Grokking SimplicityA function factory is a function that creates and returns other functions, often with a shared behavior or configuration.
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  Essential TypeScript 5, Third EditionA factory function is a function pattern that creates and returns objects or other configured values instead of requiring direct construction by the caller.
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  ASP.NET Core in Action, 3eA factory function is a function that creates and returns a configured object.
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  Fabulous Adventures in Data Structures and AlgorithmsA factory is a construction pattern that centralizes creation of objects or data-structure instances.
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  Data Pipelines with Apache Airflow, Second EditionA factory function is a function that accepts configuration and constructs recurring workflow structures such as tasks or DAGs.

Compare how 11 books explain factory →

Related concepts

• inputuses · An input is a value, information, or signal supplied to a system, computation, or interface for processing or to influence its behavior.
• const qualifieruses · A language feature that marks a value, binding, or access path as constant, restricting reassignment or modification according to the language’s rules.
• infrastructure resourceproduces · An infrastructure resource is an identifiable supporting component or service that provides technical capabilities on which applications or other system components depend.
• functionkind of · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
• design patternkind of · A design pattern is a reusable, general solution structure for a recurring software design problem in a particular context.
• hardcodingaddresses · Hardcoding is embedding fixed values, rules, configuration, or behavioral choices directly in a program or its implementation rather than supplying or deriving them separately.

This explainer was generated by Manning's knowledge graph from the text of Build a Frontend Web Framework (From Scratch). The section links point to the parts of the book it draws on.