title: What's the biggest BigInt value in js as per spec
body: <p>It turns out (outer a bit of thought it's more obvious but whatever) that <a href="https://developers.google.com/web/updates/2018/05/bigint" rel="noreferrer">BigInt</a> recently introduced to javascript has a limit:</p>
  
  <p><a href="https://i.stack.imgur.com/tTAZT.png" rel="noreferrer"><img src="https://i.stack.imgur.com/tTAZT.png" alt="enter image description here"></a></p>
  
  <p>My question would be - is there a constant similar to <code>Number.MAX_SAFE_INTEGER</code> but for BigInt? </p>
  
  <p>This snippet of code:</p>
  
  <pre><code>   let a = 2n, step = 1;
     try{while(true) {
        console.log(step); 
        a=a**2n; step++
     }} catch(e){ console.log(e)}
  </code></pre>
  
  <p>Shows that the limit is about (step = 32) - at least in Chrome. But I wonder what it this value as per spec.</p>