Building a Fluent API in TypeScript


Ryan Hayes


Who is Ryan?

JS/.NET Engineer

Prefer Ember to Angular and React (for big stuff)

Love TypeScript

Good at Google-ing

  • Twitter: @RyannosaurusRex
  • Web:
  • Dat Snapchat: ItsRyanOh
  • Wherever Social Medias Are Sold

What's a


Method Chaining in jQuery

Each method's return value is the updated element.

Method Chaining in Gulp

Each .pipe() is a new line of configuration.

Method Chaining is:

  • Passing the the context to the next method through the return value of the previous method.
  • Good for modifying a thing (changing state)
  • Sequence of things that happen w/in a context
  • Short, sweet, and to the point

Fluent APIs

  • Basically Method Chaining
    • With a hierarchy
    • And Sentinel Value
  • Great for
    • Builder Objects
    • Queries
    • Configuration
    • Sequences
  • Bad For
    • Complexity inside the API
    • Can design yourself into a corner
    • Most regular things

Key Tips

  • Be intentional about your API

  • TDD shines with Fluent APIs

  • Watch sentinel methods that rely on children (transactions)