title: What is the meaning of "foo(...arg)" (three dots in a function call)?
body: <p>Can someone tell what is "..." in the below code in the "Intro to Angular" example?</p>
  
  <pre><code>getHeroes() {
      this.backend.getAll(Hero).then( (heroes: Hero[]) =&gt; {
        this.logger.log(`Fetched ${heroes.length} heroes.`);
        this.heroes.push(...heroes); // fill cache
      });
  </code></pre>