<pre><code class="language-javascript">
/**
 * @param {any} input
 * @return {(observable: Observable) =&gt; Observable}
 * returns a function which trasnform Observable
 */
function map(transform) {
  return (source) =&gt; {
    return new Observable((subscriber) =&gt; {
      const originalNext = subscriber.next;
      subscriber.next = (value) =&gt; {
        const newValue = transform(value);
        originalNext.call(subscriber, newValue); 
      };
      source.subscribe(subscriber);
    });
  }
}
</code></pre>


This is my accepted solution

This is a follow-up on 57. create an Observable. There are a lot of operators for Observable, if we think of Observable as event stream, then modifyin…

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