JSFiddle - React, Tailwind, and code Playground

JavaScript

function decodeHTMLEntities(str) {
return str.replace(/&#(\d+);/g, function(match, dec) {
return String.fromCharCode(dec);
});
};
 
var encodeHtmlEntity = function(str) {
var buf = [];
for (var i=str.length-1;i>=0;i--) {
buf.unshift(['&#', str[i].charCodeAt(), ';'].join(''));
}
return buf.join('');
};

alert(encodeHtmlEntity('ü<&#47;script>'))