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YOUSEFUL / FILEMAKER

Youseful JavaScript: FAQ, examples and tutorial

Learning center · Function reference

Use YsflJS.fmx64 for embedded JavaScript or external Node.js execution. These examples explicitly select the embedded engine and need no Node installation.

FAQ

Do I need Node.js? Not for mode=inproc. The embedded engine handles standard JavaScript and JSON. Use mode=process or mode=worker for Node-specific APIs such as require, and install Node separately for those modes.

What does Run return? The completion value; arrays and objects become JSON. When there is no value, captured console output is used. Output returns console text and Error provides the full error/stack information.

Will variables persist? Embedded and worker globals can persist between calls. Process mode starts a fresh interpreter per call. Reset clears the working scope; Stop ends a worker. Use unique names when sharing an interpreter across scripts.

Can I await a Promise? The current API does not await returned Promises. A Promise result is not a completed HTTP response. Use synchronous calculations for these examples; use the HTTP/Curl plug-ins for their documented network calls.

Examples

Calculate a sum:

filemaker
YsflJs_Run ( "[1,2,3].reduce((sum, n) => sum + n, 0)" ; "mode=inproc" )

Result: 6.

Return an object as JSON:

filemaker
YsflJs_Run ( "({brand: 'Youseful', count: 3})" ; "mode=inproc" )

Result: {"brand":"Youseful","count":3}.

Tutorial

Standalone sample scripts: JavaScript totals.

Goal: calculate line totals from a JSON array without constructing JavaScript source from user data.

  1. Create Youseful - JavaScript totals.
  2. Add these steps. The data travels through fm.param, separate from the code.
filemaker
Set Variable [ $rows ; Value: "[{\"sku\":\"A1\",\"qty\":3,\"price\":10},{\"sku\":\"B2\",\"qty\":1,\"price\":7}]" ]
Set Variable [ $json ; Value: YsflJs_Run (
    "JSON.parse(fm.param).map(row => ({sku: row.sku, total: row.qty * row.price}))" ;
    "mode=inproc timeout=15¶param=" & $rows
) ]
Set Variable [ $error ; Value: YsflJs_LastError ]
If [ $error <> 0 ]
    Set Variable [ $detail ; Value: YsflJs_Error ]
    Show Custom Dialog [ "JavaScript failed" ; $detail ]
    Exit Script [ Text Result: $json ]
End If
Show Custom Dialog [ "Line totals" ; JSONFormatElements ( $json ) ]
  1. Run it. Ignoring JSON formatting, expect:
json
[{"sku":"A1","total":30},{"sku":"B2","total":7}]
  1. Change A1's quantity to 4 and run again. Its total becomes 40.

Troubleshooting

Put param= last on its option line. Use compact JSON without literal line breaks in that option. Embedded JavaScript has no Node require; select a Node mode for Node-specific code. If a failure occurs, keep the returned result and capture Error before another script call replaces the diagnostic.