buildUserScriptSource method

@protected String buildUserScriptSource(WebViewUserScript userScript, { required bool platformHandlesMainFrameOnly, })

Builds the source installed by a platform user-script implementation.

Registered scripts execute in a consistent private function scope. Scripts that need to expose state to later page code must assign it explicitly through globalThis. Set platformHandlesMainFrameOnly when the native API can perform frame filtering without changing the script source.

Implementation

@protected
String buildUserScriptSource(
  WebViewUserScript userScript, {
  required bool platformHandlesMainFrameOnly,
}) {
  final String scopedSource =
      '''
(function() {
${userScript.source}
}).call(globalThis);
''';
  final String globalThisCompatibility = '''
if (typeof globalThis === 'undefined') {
window.globalThis = window;
}
''';
  if (userScript.forMainFrameOnly && !platformHandlesMainFrameOnly) {
    return '''
(function() {
$globalThisCompatibility
if (globalThis.top !== globalThis) {
  return;
}
$scopedSource
}).call(globalThis);
''';
  }
  return '''
$globalThisCompatibility
$scopedSource''';
}