I'm deploying a zimlet that insert metadata at documents with this code
var titleS = document.createElement ("span");
titleS.className = "Yflickr_hLeft";
titleS.appendChild (document.createTextNode ("Title (Necessary): "));
var titleI = document.createElement ("input");
titleS.appendChild (titleI);

var filenameS = document.createElement ("span");
filenameS.className = "Yflickr_hLeft";
filenameS.appendChild (document.createTextNode ("Filename (Necessary): "));
var filenameI = document.createElement ("input");
filenameS.appendChild (filenameI);

so i've the two metadata, title and filename.

I want that the insert of metadate is required (now it's possbile null field)

how do this?