JXA

JavaScript for Automation (JXA) automates macOS apps via the Application() bridge. It runs on JavaScriptCore (ES5).

Language Constraints

• Use var (not let/const)
• Use for-loops (JXA arrays lack .map(), .filter(), .forEach())
• Return a JSON string from run() (not an object)

// WRONG: JXA arrays don't have .map()
// var names = app.windows().map(function(w) { return w.name(); });

// CORRECT: use a for-loop
var windows = app.windows();
var names = [];
for (var i = 0; i < windows.length; i++) {
  names.push(windows[i].name());
}

Script Files

Script files define a function run(argv) entry point. osascript calls it automatically and prints the return value. The function must be named run, not _run.

#!/usr/bin/env osascript -l JavaScript
function run(argv) {
  var finder = Application("Finder");
  var items = finder.desktop.items();
  var names = [];
  for (var i = 0; i < items.length; i++) {
    names.push(items[i].name());
  }
  return JSON.stringify(names);
}

Tips

• Use properties() for batch reads instead of individual getters
• Use .whose() for filtering when the app supports it (pushes work to the app)
• Application.currentApplication() accesses the current app context
• Extract sdef for any app: sdef /Applications/AppName.app