<pre class="shiki github-dark shaku"><code>/** * @param { (...args: any[]) =&gt; any } fn * @returns { (...args: any[]) =&gt; any } */const PLACEHOLDER = "_"function curry(fn) { curry.placeholder = PLACEHOLDER function carried(...args) { // Before call fn with args need to: // -args array has more or equals arguments as in fn.length // -ensure, in args no left PLACEHOLDERS // -args length can be bigger than we need, we have to slice args from 0 up top fn.length if (args.length &gt;= fn.length &amp;&amp; !args.slice(0, fn.length).includes(PLACEHOLDER)) { return fn.apply(this, args) } else { return (...args2) =&gt; { // replace placeholders in args with values // we have to replace placeholders in this place because here // we will have access to all arguments that function has been called // Iterate over args and replace placeholders with values from args2. // (shift mutate original array) everytime we make shift, it get's smaller const value = args.map(item =&gt; item === PLACEHOLDER &amp;&amp; args2.length ? args2.shift() : item) console.log(value) return carried(...value.concat(args2)) } } } return carried}const join = (a, b, c) =&gt; { return `${a}_${b}_${c}`}const curriedJoin = curry(join)const _ = curry.placeholderconst hello_world = curriedJoin("Hello", _, "world")const hello_beautiful_world = curriedJoin("Hello", _, "world")("beautiful")const hello_dangerous_world = curriedJoin("Hello", _, "world")("dangerous")</code></pre>

Curry placeholders with EXAMPLES and EXPLANATION

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…