docs.sheetjs.com/docz/docs/03-demos/10-extensions/06-osa.md

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Open Scripting Architecture (OSA), a built-in feature in macOS introduced in 1993, enables users to communicate with applications with a standardized language and grammar. macOS releases starting from Yosemite (OSX 10.10) include native support for scripting with JavaScript.

The Standalone scripts can be parsed and evaluated from the JS engine. Once evaluated, the XLSX variable is available as a global. A JS stub can expose methods from AppleScript scripts.

:::note

This demo was last tested on 2023 April 18 in macOS Monterey.

:::

Integration details

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 standalone script and test file:

{\ curl -LO https://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