Define custom functions
Flux’s functional syntax lets you define custom functions. Learn the basics of creating your own functions.
On this page:
- Function definition syntax
- Custom function examples
- Create a custom transformation
- Define functions with scoped variables
Function definition syntax
The basic syntax for defining functions in Flux is as follows:
// Basic function definition syntax
functionName = (functionParameters) => functionBody
- functionName: Name to use to execute the function.
- functionParameters: Comma-separated list of parameters passed into the function.
- functionBody: Operations on function parameters.
Define parameter defaults
Use the = assignment operator to assign a default value to function parameters
in your function definition:
functionName = (param1=defaultVal1, param2=defaultVal2) => functionBody
Defaults are overridden by explicitly defining the parameter in the function call. Parameters without default values are considered required parameters.
Custom function examples
Create a custom transformation
A transformation is a function that takes a stream of tables as input, operates on the input, and then outputs a new stream of tables.
The pipe-forward operator (|>)
pipes data from the previous identifier or function forward into a transformation.
To use piped-forward data, assign a function parameter to the
pipe-receive operator (<-).
In the following example, the function x() receives piped-forwarded data and assigns it to the t parameter.
In the function body, t is piped forward into other operations to generate output.
x = (t=<-) => t |> //...
Custom transformation examples
Define functions with scoped variables
To create custom functions with variables scoped to the function,
- Enclose your function body in a
block (
{}). - Use a
returnstatement to return a specific variable.
functionName = (param) => {
exampleVar = "foo"
return exampleVar
}
Example functions with scoped variables
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