document.getElementById('c').addEventListener('click', changeColor('red'));
document.getElementById('d').addEventListener('click', changeColor('blue'));
function changeColor (newColor) {
var element = document.getElementById("textvc");
element.style.color = newColor;
}
<p id="textvc">wdadwadont</p>
<button id="c">c</button>
<button id="d">d</button>