Edit in JSFiddle

function verify(text) {
  let openingBrackets = ["{", "<", "("];
  let closingBrackets = ["}", ">", ")"];
  let valid = true;
  let rgxp = null;

  for(let i=0,l=openingBrackets.length; i<l; i+=1) {
  	if (text.indexOf(openingBrackets[i]) > -1 ||
      text.indexOf(closingBrackets[i]) > -1) {
      rgxp = eval("new RegExp(/\\"+ openingBrackets[i] +"(.)*\\"+ closingBrackets[i] +"/g)");
      valid = rgxp.test(text);
    }
  }
  return valid;
}

let testCases = ["{}", "eou{u}", "++<{eu}", "<{>}oeuoeu"];
let resNode = document.getElementById('result');

for (let i=0; i< testCases.length; i+=1) {
resNode.appendChild(document.createTextNode(verify(testCases[i])+' '));
}