Type Annotations
Specify your intentions as type annotations in code, and Flow will check that
everything is behaving as expected.
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Weak types in JS
What is Flow?
Introduction Flow Types Tools Conclusion
Working with Flow Summary and further
learning
Tooling for Flow
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Variable Types
When you declare a new variable, optionally declare its type.
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Function Types
Functions have two places where types are applied: Parameters (input) and the
return value (output).
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Maybe Types
Maybe types are for places where a value is optional and you can create them by
adding a question mark in front of the type such as ?string or ?number.
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Optional Parameters / Properties
Functions / objects can have optional parameters / properties where a question
mark ? comes after the parameter name.
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Literal Types
Flow can also use literal values as types.
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Object Types
You can annotate the properties of an object with types.
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Reusable Types with Type Aliases
When you have complicated types that you want to reuse in multiple places, you
can alias them in Flow using a type alias.
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Union Types
Sometimes it’s useful to create a type which is one of a set of other types.
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Interface Types
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Importing and Exporting Types
You can export type aliases, interfaces, and classes from one file to another.
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Weak types in JS
What is Flow?
Introduction Flow Types Tools Conclusion
Working with Flow Summary and further
learning
Tooling for Flow
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Flow Tooling
Linter
Compiler
You’ll need to setup a compiler
to strip away Flow types from
your final code.
Install Flow per project to
perform type checking on your
JS files.
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Weak types in JS
What is Flow?
Introduction Flow Types Tools Conclusion
Working with Flow Summary and further
learning
Tooling for Flow
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Type Checking in Javascript
with Flow
Yos Riady
yos.io
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