Make a colorful combobox

test.html

<select id="test">
    <option id="test1">test1</option>
    <option id="test2">test2</option>
    <option id="test3">test3</option>
    <option id="test4">test4</option>
    <option id="test5">test5</option>
</select>

test.js

var testCombo = document.querySelector('#test');
document.querySelector('#test1').style.color = "red";
document.querySelector('#test2').style.color = "blue";
document.querySelector('#test3').style.color = "yellow";
document.querySelector('#test4').style.color = "gray";
document.querySelector('#test5').style.color = "green";

testCombo.addEventListener('change', function(){
    testCombo.style.color = testCombo.options[testCombo.selectedIndex].style.color;
}, false);

testCombo.style.color = testCombo.options[testCombo.selectedIndex].style.color;