JSFiddle - React, Tailwind, and code Playground

HTML

<form name="form1" method="post" action="">
    <input type="text" id="txtTitle" name="txtTitle" mand="Y" value="The Red Album" />
    <input type="button" name="saveme" value="Save" onclick="doStuff()"
</form>

JavaScript

//standard DOM functions trying to access custom attribure: 'mand'
//MUST RUN IN ==INTERNET EXPLORER==

function doStuff() {
    //get the name attribute - all work
    alert(document.getElementById("txtTitle").name);
    alert(document.form1.txtTitle.name);
        alert(form1.txtTitle.name);

    //get the mand attribute - none work
    alert(document.getElementById("txtTitle").mand);
    alert(document.form1.txtTitle.mand);
    alert(form1.txtTitle.mand);

    //using DOM collections
    alert(document.forms(0).elements(0).id);     //works
    alert(document.forms(0).elements(0).mand);   //doesn't work
}