JSFiddle - React, Tailwind, and code Playground
HTML
<button onclick="test" >A button element</button>
JavaScript
console.log('selected: %d', $("button[onclick^='test']").length);
console.log('attr onclick: %s', $('button').attr('onclick'));
<button onclick="test" >A button element</button>
console.log('selected: %d', $("button[onclick^='test']").length);
console.log('attr onclick: %s', $('button').attr('onclick'));