title: Using BigInt in TypeScript
body: <p>I believe I should be able to use BigInt now in TypeScript...but changing some code base to use it and I get "Cannot find name 'BigInt'. (2304)" any thought on why I am getting this error?</p>
  
  <pre><code>$ cat test.ts 
  let x = BigInt(123)
  console.log(x.toString())
  
  $ tsc test.ts 
  test.ts:1:9 - error TS2304: Cannot find name 'BigInt'.
  
  1 let x = BigInt(123)
            ~~~~~~
  
  
  Found 1 error.
  </code></pre>
  
  <p>How do I start using BigInt now within TypeScript?</p>