please convert it to a fetch function function

function handleSubmitButton() {

let userText = document.getElementById('userTextField').value

if (userText && userText != '') {

let userRequestObj = {text: userText}

let userRequestJSON = JSON.stringify(userRequestObj)

document.getElementById('userTextField').value = ''

//alert ("You typed: " + userText);

let xhttp = new XMLHttpRequest()

xhttp.onreadystatechange = function() {

if (this.readyState == 4 && this.status == 200) {

console.log("data: " + this.responseText)

console.log("typeof: " + typeof this.responseText)

//we are expecting the response text to be a JSON string

let responseObj = JSON.parse(this.responseText)

movingString.word = responseObj.text

drawCanvas()

}

}

xhttp.open("POST", "userText") //API .open(METHOD, URL)

xhttp.send(userRequestJSON) //API .send(BODY)

}

}