use getElementById() or getElementByClass() and find elements from the console.
For example:
<html> <head> <title>Ejemplo getElementById</title> </head> <body> <p id="para">Cualquier texto acá</p> <button onclick="changeColor('blue');">Azul</button> <button onclick="changeColor('red');">Rojo</button> </body> </html> var elem = document.getElementById('para'); elem.style.color = red;and you will change the color of the text to red.