how to pop up datalist options for input tag in html

I’m currently trying to add to my datalist for my input text field in html. The way I do it is to retrieve text from backend and dynamically generate options in datalist, however, after I retrieve all texts at my frontend and generate option to datalist, there is only one option display instead all.

Here is the way I add option to my datalist:

async function getSuggestedWords(event) {
    let datalist = document.getElementById("suggestions");
    let text = document.getElementById("q").value;
    let http = new XMLHttpRequest();
    http.responseType = "json";
    // let str = "";
    http.onload = async function() {
        if (this.readyState == 4) {
            let  {suggestions}   = http.response;

            for (let suggest of suggestions) {
                console.log(suggest.term);
                let s = document.createElement('option');
                s.setAttribute("value", suggest.term);
                datalist.appendChild(s);
            }
        }
    }

    const url = `http://localhost:8080/api/suggest?q=${text}`;
    await http.open("GET", url);
    await http.send();
}

here is my html:

        <label for="q">Input</label>
        <input type="text" name="q" id="q" list="suggestions" onchange="getSuggestedWords(event)" autocomplete="on">
        <datalist id="suggestions">
        </datalist>