Watch Mode

Basic Watch

Re-run recipe when files change:

jake -w build

Jake watches files based on:

• File dependencies in file recipes
• @watch directives in tasks

Watch Specific Patterns

jake -w "src/**/*.ts" build

Watch Directive

Mark files to watch in a task:

task build:
    @watch src/*.ts
    npm run build

Multiple patterns:

task dev:
    @watch src/**/*.ts tests/**/*.ts
    npm run dev

Watch with Verbose Output

jake -w -v build

Shows which files triggered the rebuild.

Conditional Watch Behavior

Use is_watching() to adjust behavior:

task build:
    @if is_watching()
        echo "Watch mode: skipping expensive lint"
    @else
        npm run lint
    @end
    npm run build

Combining with Other Flags

# Watch with verbose output
jake -w -v build

# Watch with parallel jobs
jake -w -j4 build