Async Function Must Return A Boolean Value

I have a method that I am calling on the onsubmit event in the form tag. So I need a true or false to be returned from the method. I use an API to retrieve data, and according to t

Solution 1:

GetPolygonID() function returns a Promise, so it must be either called with await or you can call then upon it:

var res = awaitGetPolygonID();

GetPolygonID().then(res =>console.log(res));

You can make the whole function async:

asyncfunctionGetPolygonID() {
    document.getElementById("displayerror").innerHTML = "";
    var retrievedpoly = document.getElementById('polygondetails').value;
    var parts = retrievedpoly.split('coordinates');
    var parttoadd = parts[1].substring(0, parts[1].length - 2) + "}";
    console.log(parttoadd);

    var myx = '{"name":"Polygon OneTwoThree","geo_json":{"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates' + parttoadd;
    var url = 'http://api.agromonitoring.com/agro/1.0/polygons?appid=apiid';

    const response = awaitfetchPoly(url, myx);
    const data = response.json();
    const errorCheck = CheckInfo(data);
    console.log("2: " + errorCheck);
    return errorCheck;
}

Using an async function for a form validation, you can do this:

functiononSubmit(form) {
    GetPolygonID().then(res => res ? form.submit() : null);
    returnfalse;
}
...
<form method="POST" onsubmit="return onSubmit(this);">
...