How deeply does The Joy of JavaScript cover dynamic module system?

Explains runtime module creation, conditional access, syntax differences, and optimization tradeoffs without detailing loader internals.

Dynamic module system

As explained in The Joy of JavaScript

A module system in which dependencies and module interfaces are determined programmatically at runtime rather than by static language syntax.

A dynamic module system determines dependencies and module interfaces programmatically at runtime. Code or a module loader creates the module definition in memory, allowing conditional access to modules or parts of modules. section 6.3

Dynamic and static systems differ in how they express module boundaries:

CommonJS and RequireJS use ordinary JavaScript function calls such as require(...). section 6.3
ESM uses native import and export syntax, placing imports statically so runtimes and tools can map dependencies ahead of execution. section 6.3
Dynamic loading supports conditional inclusion, while static definitions support preloading and removal of unreachable package code. section 6.3

CommonJS state versus ESM bindings

A CommonJS calculator exports feePercent, netTotal, and setFeePercent. Changing a destructured feePercent locally does not change the value used by netTotal; calling setFeePercent does. The ESM version exposes the same operations, and its imported feePercent reflects the setter’s update.

How The Joy of JavaScript covers it

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Related concepts

module.exportsuses · module.exports is the CommonJS property whose assigned value is exposed to other modules when they require the module.
requireuses · require is a CommonJS function that synchronously loads a module and returns its exported value.
dynamically loaded moduleused by · A dynamically loaded module is an application module whose code is loaded on demand when navigation reaches a route that requires it.
modulecontrasts with · A module is a distinct, bounded software unit that groups related code or functionality and provides an organizational or interaction boundary within a larger system.
static module systemcontrasts with · A module system in which module dependencies and exports are declared by fixed language syntax that can be analyzed before execution.

This explainer was generated by Manning's knowledge graph from the text of The Joy of JavaScript. The section links point to the parts of the book it draws on.