JSFiddle - React, Tailwind, and code Playground
HTML
<input type="button" id="a" value="SUBMIT" onclick="fnSubmitForm(this);">
<input type="button" id="b" value="SUBMIT" onclick="fnSubmitForm(this);">
<input type="button" id="c" value="SUBMIT" onclick="fnSubmitForm(this);">
JavaScript
function fnSubmitForm(el) {
console.log(el.id);
}