Strange Loop

Flow - Am I Your Type?

Flow is an open source tool from Facebook that is "a static type checker, designed to find type errors in JavaScript programs". It supports adding types gradually to variables, parameters, return values, object properties, and array elements. Flow even catches some errors without adding types by using type inference and flow analysis.

Flow supports many types including primitives, functions (with specified signatures), arrays, objects, built-in classes, custom classes, and generic (parameterized) classes.

Flow is similar to Microsoft TypeScript and mostly uses the same syntax for specifying types. However, TypeScript is also a transpiler. One benefit of using Flow is that Babel can be used for transpiling. Babel typically implements new ECMAScript features before TypeScript.

This talk covers everything you need to know to get started using Flow, including integration with Babel, ESLint, editors, and IDEs.

Mark Volkmann

Mark Volkmann

Object Computing, Inc.

Mark Volkmann is a partner at Object Computing, Inc. (OCI) in St. Louis where he has provided software consulting and training since 1996. As a consultant, Mark has assisted many companies with JavaScript, Node.js, React, AngularJS, jQuery, and Java application development. He has created and taught many courses on topics including React, AngularJS, Node.js, jQuery, JavaScript, HTML5, CSS3, Ruby, Java, and XML. Mark is a frequent presenter at St. Louis area user groups. He has written for XML Journal and the No Fluff Just Stuff magazine. He has presented at the MidwestJS, Jfokus, Strange Loop, No Fluff Just Stuff, and XML DevCon conferences. Mark frequently writes articles on various software development topics. These can be found at