Extending

Extending tasks avoids a lot of duplicated task definitions in bigger projects and monorepos. With the extend property, a task uses another task's configuration as a template.

The following sections and examples use the two predefined tasks in the build.tsc.yaml file — one of the ready-made templates shipped under best-practices/. Copy it into your project (or include it directly) to follow along.

tasks:
  install:
    src:
      - package.json
      - package-lock.json
    generates:
      - node_modules
    cmds:
      - npm ci
      
  build:
    deps: [ install ]
    src:
      - tsconfig.json
      - src
    cmds:
      - node_modules/.bin/tsc
    generates:
      - dist

Extend a taskCopy Anchor Link

Extending tsc:build uses all of its properties as a base. If nothing else is defined, the result is an exact copy that runs in the working directory of the current build file.

tasks:
  build:
    extend: tsc:build
    
includes:
  tsc: ./build.tsc.yaml

Override properties in an extendCopy Anchor Link

An extending task can override any property, whether the base defines it or not. In this example the dependencies are cleared, so the task runs without depending on install.

tasks:
  build:
    extend: tsc:build
    deps: []
    
includes:
  tsc: ./build.tsc.yaml

Naming the base taskCopy Anchor Link

extend uses the same <prefix>:<task> addressing as dependencies: the part before the colon is the include (or reference) prefix, and the part after it is the task name in that file. extend: tsc:build means "the build task from the file included as tsc". To extend a task in the same file, use its bare name (extend: build-base).