<pre class="shiki github-dark shaku"><code>// This is a JavaScript coding problem from BFE.dev/** * @param { (...args: any[]) =&gt; any } fn * @returns { (...args: any[]) =&gt; any } */function curry(fn) { // Return a function named curried that we can call again and again. return function curried(...args) { // Check if we have enough arguments and no placeholders are left // in the positions needed by the original function. if ( args.length &gt;= fn.length &amp;&amp; args.slice(0, fn.length).every( (el) =&gt; el !== curry.placeholder ) ) { // If all required arguments are available, call the original function. return fn.call(this, ...args); } else { // If some arguments are missing, return a new function // so we can pass more arguments later. return function (...newArgs) { let i = 0; // Go through the old arguments one by one. let mergedArray = args.map((el) =&gt; { // If the current argument is a placeholder, // replace it with the next new argument. if ( el === curry.placeholder &amp;&amp; i &lt;= newArgs.length ) { return newArgs[i++]; } // If it is not a placeholder, keep the old argument. return el; }); // Add any new arguments that were not used to fill placeholders. mergedArray.push(...newArgs.slice(i)); // Call curried again with the combined arguments. return curried.call(this, ...mergedArray); }; } };}// Create a special value that we can use as a placeholder.curry.placeholder = Symbol();</code></pre>

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This is a follow-up on 1. implement curry() please implement curry() which also supports placeholder. Here is an example const join = (a, b, c) => { r…