Hyphenated names of attributes in JavaScript

Custom attributes can contain hyphens in their names, like this:

<div id="elem" data-my-test="1000"></div>

To refer to such attributes, use camelCase:

let elem = document.querySelector('#elem'); console.log(elem.dataset.myTest);

Given the following code:

<div id="elem" data-product-price="1000" data-product-amount="5"> apples </div>

Make it so that when you click on the div, the purchase price is added to the end of its text, equal to the price multiplied by the quantity.