<pre class="shiki github-dark shaku"><code>&gt; Promise.resolve(1) .then(console.log)// &gt; 1</code></pre>
Is the same as
<pre class="shiki github-dark shaku"><code>&gt; new Promise((resolve) =&gt; resolve(1)) .then((val) =&gt; console.log(val))// &gt; 1</code></pre>
Therefore,
<pre class="shiki github-dark shaku"><code>Promise.then(() =&gt; 2) .then(console.log)// &gt; 2</code></pre>
But don't forget that if you don't use the new value you are chaining, it won't be used, e.g.
<pre class="shiki github-dark shaku"><code>Promise.resolve(1) .then(() =&gt; 2) .then(console.log)// &gt; 2 # as 1 isn't passed in the first 'then', e.g. .then(num =&gt; num + 2)</code></pre>
And you can't have numbers in .then calls, they need to be functions, ts throws this error, therefore that goes onto the reject pile
and we skip over it
<pre class="shiki github-dark shaku"><code>Promise.resolve(1) .then(3) // Argument of type '3' is not assignable to parameter of type '(value: number) =&gt; number | PromiseLike&lt;number&gt;'.ts(2345)</code></pre>
<pre class="shiki github-dark shaku"><code>Promise.resolve(1).then(Promise.resolve(4)).then(console.log)// &gt; 1</code></pre>
<code>then(Promise.resolve(4))</code>
<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then">https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then</a>
<blockquote>
returns another pending promise object, the resolution/rejection of the promise returned by then will be subsequent to the resolution/rejection of the promise returned by the handler. Also, the resolved value of the promise returned by then will be the same as the resolved value of the promise returned by the handler.
</blockquote>
<pre class="shiki github-dark shaku"><code>Promise.resolve(1) // 1.then(() =&gt; 2) // 2 (as 1 isn't used).then(3) // skip.then((value) =&gt; value * 3) // 2 * 3 == 6.then(Promise.resolve(4)) // creates a Pending promise.then(console.log) // funnels 6 into console.log</code></pre>

Detailed explanation 

What does the code snippet to the right output by console.log?…