<pre class="shiki github-dark shaku"><code>type ProduceFunc = &lt;T&gt;(base: T, receipe: (draft: T) =&gt; any) =&gt; void;const produce: ProduceFunc = (base: Record&lt;string, any&gt;, recipe) =&gt; { let copy = JSON.parse(JSON.stringify(base)); recipe(copy); if (equal(base, copy)) { copy = base; } return copy;}function equal(base: any, copy: any): boolean { if (typeof base !== typeof copy) return false; if (typeof base !== "object") return base === copy; if ((base === null &amp;&amp; copy !== null) || (base !== null &amp;&amp; copy === null)) return false; let isEqual = true; for (const key in copy) { if ((key in base) &amp;&amp; equal(base[key], copy[key])) { copy[key] = base[key]; } else { isEqual = false; } } for (const key in base) { if (!(key in copy)) { return false; } } return isEqual;}</code></pre>

Solution

In 12. implement Immutability helper, we are asked to implement immutability helpers. These helpers requires extra effort for us to remember how to us…