如何从 Flutter Web 调用 JS 函数?

How to call a JS function from Flutter Web?

我想从 Flutter Web 应用程序调用一个简单的 JS 函数:

<script>
    function alertMessage(text) {
          alert(text)
    }
</script>

我怎样才能做到这一点?

main.dart:

void onTap(){
    ///This is where I want to call the JS function...  alertMessage();
}

dart:js library

import 'dart:js';

main() => context.callMethod('alert', ['Hello from Dart!']);