JSFiddle - React, Tailwind, and code Playground
HTML
<div id="test.anthony" alt="test" width="20">JavaScript
var selector = "test\\.anthony";
var selector2 = "test.anthony";
selector3 = selector2.replace(/\./g, "\\\\.");
console.log("1."+$("#test\\.anthony").attr("width"));
console.log("2."+$('#' + selector).attr("width"));
console.log(selector3);
console.log("3."+$('#' + selector3).attr("width"));