# Modifier key tracking in JavaScript

Using the `Event` object, you can find out if the `Ctrl`, `Alt`, and `Shift` keys were pressed at the time of the event. This is done using the properties `ctrlKey`, `altKey` and `shiftKey` - they have the value `true` or `false` depending on whether this key was pressed at the time of the event or not.

Let's look at an example. Let's say we have the following button:

`<button id="elem">text</button>`

By clicking on the button, we will display a message about whether one of the keys `Ctrl`, `Alt` and `Shift` was pressed:

`let elem = document.querySelector('#elem'); elem.addEventListener('click', function(event) { if (event.ctrlKey) { console.log('Ctrl is pressed'); } if (event.altKey) { console.log('Alt is pressed'); } if (event.shiftKey) { console.log('Shift is pressed'); } });`

Given an element. Make it turn red when clicked, but only if the `Alt` key is pressed at the time of the click.

Let's say you have the list `ul` with tags `li`:

`<ul id="elem"> <li>text</li> <li>text</li> <li>text</li> <li>text</li> <li>text</li> </ul>`

Make it so that when you click on any `li`, the number `1` is added to the end of its text if the `Ctrl` key is pressed, and the number `2` if `Shift` is pressed.

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