title: Is there a reverse logical nullish assignment?
body: <p>So the <code>??=</code> operator assigns the value to the variable only if the current stored value is nullish.</p>
  <p>Maybe I'm missing the obvious but I can't think of a slick solution (without if statements) to only assign if <strong>the value is not nullish</strong>?</p>
  <p><em>I'm using nodeJS to give a bit more context</em>.</p>
  <hr />
  <p>I want</p>
  <pre class="lang-js prettyprint-override"><code>let x r??= 2;
  // Updates 'x' to hold this new value
  x r??= undefined;
  // Has no effect, since the value to assign is nullish
  console.log(x); // 2
  </code></pre>
  <p><strong>EDIT</strong>
  to give more clarity to my problem:</p>
  <p>I want a variable only to be assigned a <strong>new value</strong>, if that new value is not nullish.</p>
  <pre class="lang-js prettyprint-override"><code>let iceCream = {
      flavor: 'chocolate'
  }
  
  const foo = 2.5
  const bar = undefined;
  
  iceCream.price r??= bar
  // does not assign the new value because it is nullish
  console.log(iceCream.price) // expected to be error, no such property
  
  iceCream.price r??= foo
  // assigns the new value because it is not nullish but a float
  console.log(iceCream.price) // expected to be 2.5
  
  iceCream.price r??= bar
  // does not assign the new value because it is nullish
  console.log(iceCream.price) // expected to still be 2.5
  </code></pre>