How to register a class in a .js file of QML using C++?

[yangsiyu]

How to register a class in a .js file of QML using C++? For example, I have an OaiClient in C++ and want to use ‘const client = new OaiClient’ in JavaScript.
I checked the documentation, which states: You cannot use the globalObject() function to change the global object of a QQmlEngine.
What should I do?

[Axel Spoerl]

Good morning and welcome to the Qt Forum,
how have you written your C++ extension?
If you follow this documentation, it will be accessible from QML and Javascript.

[yangsiyu]

@Axel-Spoerl Thank you for your reply. I have read this document. What I want to do is something similar to the following:

import QtQuick

import "backend.js" as Backend

Item {
    Component.onCompleted: {
        Backend.func()
    }
}

// backend.js
function func() {
    const obj = new OaiClient()  // OaiClient is a JS class registered from C++
}

What I want is to be able to register a C++ class to a JS file, and the JS file can use the new keyword to instantiate this class.

[yangsiyu]

@Axel-Spoerl I found that the following code works:

   QQmlApplicationEngine engine;
    auto ctor = engine.evaluate(R"(
        (function() {
            this.name = "test"
            this.create = function(){
                return "hello world!"
            }
        })
    )");
    engine.globalObject().setProperty("OaiClient", ctor);

However, I don’t understand what the documentation means when it says that the globalobject properties should not be modified, and I’m unsure what the implications of doing so might be.