I have an SPFX Web Part (*No Framework*) and would like to add an onClick event to my which will call my function `swap()`. 

Code:

```
export default class ExpandableIFrameWebPart extends 
BaseClientSideWebPart<IExpandableIFrameWebPartProps> {

public render(): void {

if (!this.renderedOnce){
  SPComponentLoader.loadCss('https://use.fontawesome.com/releases/v5.0.9/css/all.css');
}

this.domElement.innerHTML = `
  <div class="${ styles.expandableIFrame }">
    <i id="rArrow" class="fas fa-arrow-circle-right" onClick="swap()"></i>
    <iframe id="flip" class="${ styles.startCollapsed }" src="https://css-tricks.com/restart-css-animation/" frameborder="0"></iframe>
  </div>`;

  function swap(){
    console.log("Triggered!");
    document.getElementById("flip").className == "expanded" ? document.getElementById("flip").className = "collapsed": document.getElementById("flip").className = "expanded";
  }
}

```

**Things I've tried:**

When I add `onClick="swap()"` or `onClick="${ this.swap() }"` to my `<i>` tag, the webpart no longer renders in the workbench. (When using the `this.swap()` method I moved the function outside of the render function)

Adding `document.getElementById("rArrow").addEventListener("Click", swap())` (with or without `this.`), there is an error that the EventListener doesn't accept 'void' types.