JSFiddle - React, Tailwind, and code Playground

Babel + JSX

function removeDuplicates(str) {
	return function filter(str) {
  
  	var newStr = str.replace(/(.*)\1{1,}/g, '$1');   
    if (newStr !== str) {
    	return filter(newStr);
    } else {
    	return newStr;
    }
    
  }(str);
}

console.log(removeDuplicates('Hellolo') === 'Helo');
console.log(removeDuplicates('Frontendendend Raccoon') === 'Frontend Racon');
console.log(removeDuplicates('<body><body></body>') === '<body></body>');