docs.sheetjs.com/docz/docs/03-demos/32-extensions/06-osa.md

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Open Scripting Architecture (OSA)¹ enables macOS app automation with scripts. OSA originally supported the "AppleScript" language. Modern macOS releases (OSX 10.10 and later) natively support JavaScript scripts using "JXA"².

SheetJS is a JavaScript library for reading and writing data from spreadsheets.

:::note Tested Environments

This demo was tested in the following environments:

macOS	Language	Date
14.3.1	AppleScript (OSA)	2024-02-21
14.3.1	JavaScript (JXA)	2024-02-21

:::

Integration details

The SheetJS Standalone scripts can be parsed and evaluated from the JS engine. Once evaluated, the XLSX global will be defined. A JS stub can expose methods from AppleScript scripts.

The following snippet reads a file into a binary string:

ObjC.import("Foundation");
function get_bstr(path) {
  /* create NSString from the file contents using a binary encoding */
  var str = $.NSString.stringWithContentsOfFileEncodingError(path, $.NSISOLatin1StringEncoding, null);
  /* return the value as a JS object */
  return ObjC.unwrap(str);
}

Loading the Library

Assuming the standalone library is in the same directory as the source file, the script can be evaluated with eval:

var src = get_bstr("./xlsx.full.min.js");
eval(src);

Parsing Files

The same method can be used to read binary strings and parse with type: "binary":

var file = get_bstr("./pres.numbers");
var wb = XLSX.read(file);

The core idea is to push the processing logic to a stub JS file.

JS Stub

The JS stub will be evaluated in the JavaScript context. The same technique from the JavaScript section works in the stub:

ObjC.import("Foundation");

function get_bstr(path) {
  var str = $.NSString.stringWithContentsOfFileEncodingError(path,  $.NSISOLatin1StringEncoding, null);
  return ObjC.unwrap(str);
}

/* this will be called when AppleScript initializes the JS engine */
eval(get_bstr("./xlsx.full.min.js"));

It is more efficient to offload as much work as possible into the stub. For example, this function parses a workbook file from the filesystem and generates a CSV without passing intermediate values back to AppleScript:

/* this method will be exposed as `wb_to_csv` */
function wb_to_csv(path) {
  /* read file */
  var filedata = get_bstr(path);
  var wb = XLSX.read(filedata, { type: "binary" });
  return XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]);
}

Loading the Stub

Assuming the stub is saved to xlsx.stub.js, the following handler creates a context and evaluates the standalone library:

on getContext()
  -- get contents of xlsx.stub.js
  set UnixPath to POSIX path of ((path to me as text) & "::")
  set libpath to POSIX path of (UnixPath & "xlsx.stub.js")
  set {src, err} to current application's NSString's stringWithContentsOfFile:libpath encoding:(current application's NSISOLatin1StringEncoding) |error|:(reference)
  if src is missing value then error (err's localizedDescription()) as text

  -- create scripting context and evaluate the stub
  set lang to current application's OSALanguage's languageForName:"JavaScript"
  set osa to current application's OSAScript's alloc()'s initWithSource:src language:lang
  return osa
end getContext

Evaluating JS Code

When calling a function, the result is an array whose first item is the value of the evaluated code. A small helper function extracts the raw result:

on extractResult(res)
  return item 1 of ((current application's NSArray's arrayWithObject:res) as list)
end extractResult

With everything defined, executeHandlerWithName will run functions defined in the stub. For example:

set osa to getContext()
set {res, err} to osa's executeHandlerWithName:"wb_to_csv" arguments:{"pres.numbers"} |error|:(reference)
extractResult(res)

Complete Demo

This example will read from a specified filename and print the first worksheet data in CSV format.

0. Download the SheetJS Standalone script and test file. Move both files to the project directory:

• xlsx.full.min.js
• pres.numbers

{\ curl -LO https://docs.sheetjs.com/pres.numbers curl -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.full.min.js}

1. Save the following script to sheetosa.js:

#!/usr/bin/env osascript -l JavaScript

ObjC.import("Foundation");
function get_bstr(path) {
  var str = $.NSString.stringWithContentsOfFileEncodingError(path,  $.NSISOLatin1StringEncoding, null);
  return ObjC.unwrap(str);
}
eval(get_bstr("./xlsx.full.min.js"));

function run(argv) {
  var filedata = get_bstr(argv[0]);
  var wb = XLSX.read(filedata, { type: "binary" });
  console.log(XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]));
}

2. Make the script executable:

chmod +x sheetosa.js

3. Run the script, passing the path to the test file as an argument:

./sheetosa.js pres.numbers

1. Save the following script to xlsx.stub.js:

ObjC.import("Foundation");
function get_bstr(path) {
  var str = $.NSString.stringWithContentsOfFileEncodingError(path,  $.NSISOLatin1StringEncoding, null);
  return ObjC.unwrap(str);
}
eval(get_bstr("./xlsx.full.min.js"));

function wb_to_csv(path) {
  var filedata = get_bstr(path);
  var wb = XLSX.read(filedata, { type: "binary" });
  return XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]);
}

2. Save the following script to sheetosa.scpt:

#!/usr/bin/env osascript
use AppleScript version "2.7"
use scripting additions
use framework "Foundation"
use framework "OSAKit"

set osa to getContext()
set {res, err} to osa's executeHandlerWithName:"wb_to_csv" arguments:{"pres.numbers"} |error|:(reference)
extractResult(res)

on getContext()
  set UnixPath to POSIX path of ((path to me as text) & "::")
  set libpath to POSIX path of (UnixPath & "xlsx.stub.js")
  set {src, err} to current application's NSString's stringWithContentsOfFile:libpath encoding:(current application's NSISOLatin1StringEncoding) |error|:(reference)

  set lang to current application's OSALanguage's languageForName:"JavaScript"
  set osa to current application's OSAScript's alloc()'s initWithSource:src language:lang
  return osa
end getContext

on extractResult(res)
  return item 1 of ((current application's NSArray's arrayWithObject:res) as list)
end extractResult

3. Make the script executable:

chmod +x sheetosa.scpt

4. Run the script (it is hardcoded to read pres.numbers):

./sheetosa.scpt

---

1. See "Introduction to AppleScript Overview" in the Apple Developer documentation for more details. ↩︎

2. See "Introduction to JavaScript for Automation Release Notes" in the Apple Developer documentation for more details. ↩︎