modulesalias

Modulesalias is a mechanism in module resolution that allows remapping module identifiers to alternate implementations or file paths during import or require resolution. It enables substituting one module for another without changing source code, supporting refactoring, environment-specific implementations, testing, and monorepo workflows.

In practice, modulesalias works by supplying a mapping from logical module specifiers to concrete locations. The mapping can be provided to bundlers, runtime loaders, or language compilers. Resolution rules determine which alias applies and in what order. Aliases may be declared statically in configuration files or registered at runtime, allowing dynamic switching of implementations.

A typical alias map associates a module name with a path or another specifier. For example, an alias might map "utils/math" to "./src/common/math/index.js" or map "api" to "./src/api/v2". Similar concepts exist across ecosystems under different names, such as path mapping in TypeScript or module aliasing in bundlers like Webpack. The term modulesalias abstracts these practices into a general concept applicable to various languages and toolchains.

Usage scenarios include simplifying refactoring by decoupling import paths from physical locations, enabling testing with mock or alternate implementations, supporting environment-specific builds, and managing dependencies in large projects or monorepos without changing source code.

Limitations include potential tooling complexity, risk of ambiguous or conflicting aliases, and the need for consistent tool support across build and runtime environments. Careful documentation of the alias map and clear resolution order are recommended.

See also: module resolution, path aliasing, aliasing, bundler configuration, monorepos.