Streamlit Javascript integration

I can’t get any js function in streamlit to work, the return value is always 0, no matter how I tried to write it. For instance

anonymous = st_javascript("""
    (() => {
        return 2;
    })()
""")

st.write(f"JavaScript returned: {anonymous}")

What am I doing wrong here? Chatgpt and claude couldn’t help, nor did I see any helpfull posts here.

Can someone provide the correct syntax?