PHP Decode

<?  const $ = q => document.querySelector(q); 
const $a = q => document.querySelectorAll(q); 
 
const boxes = $a('.box'); 
let flagbox = boxes[Math.floor(Math.random() * boxes.length)]; 
 
for (const box of boxes) { 
  if (box === flagbox) { 
    box.onclick = () => { 
      let enc = `"\u000e\u0003\u0001\u0016\u0004\u0019\u0015V\u0011=\u000bU=\u000e\u0017\u0001\t=R\u0010=\u0011\t\u000bSS\u001f"`; 
      for (let i = 0; i < enc.length; ++i) { 
        try { 
          enc = JSON.parse(enc); 
        } catch (e) { } 
      } 
      let rw = []; 
      for (const e of enc) { 
        rw['push'](e['charCodeAt'](0) ^ 0x62); 
      } 
      const x = rw['map'](x => String['fromCharCode'](x)); 
      alert(`Congrats ${x['join']('')}`); 
    }; 
    flagbox = null; 
  } else { 
    box.onclick = () => alert('no flag here'); 
  } 
}; ?>