function isBalanced(str) {
  // Ваш код здесь
}
 
console.log(isBalanced("(x + y) - (4)")); // -> true
console.log(isBalanced("(((10 ) ()) ((?)(:)))")); // -> true
console.log(isBalanced("[({()})]")); // -> true
console.log(isBalanced("(50)((")); // -> false
console.log(isBalanced("[{]}")); // -> false

function isBalanced(str) {
  const regProps = /[\(\)|\[\]|\{\}]/gm;
  const regArrows = /\(\)|\[\]|\{\}/gm;
 
  let prev = "";
  let replaced = str.match(regProps).join("");
 
  while (replaced !== prev) {
    prev = replaced;
    replaced = replaced.replace(regArrows, "");
  }
 
  return prev === "";
}
 
console.log(isBalanced("(x + y) - (4)")); // -> true
console.log(isBalanced("(((10 ) ()) ((?)(:)))")); // -> true
console.log(isBalanced("[({()})]")); // -> true
console.log(isBalanced("(50)((")); // -> false
console.log(isBalanced("[{]}")); // -> false