how can I use a JS function to change an element style in the page

Question

I need 2 simple JavaScript functions that read and change the color of a div on click. I don't want to use frames, jQuery any other means but simple html, css, JS. The code that I have wrote and doesnot work is as follows:

Randomize colours

<script>
    var colorArray = {yellow, red, blue, purple};

    function readColor () {
        color = document.getElementById("color");
            }

    function changeColor (color) {
            var randomColor = colorArray[Math.floor(Math.random() * colorArray.length)];    
        document.getElementById('color').style.backgroundColor = randomColor;
        var colors = document.getElementById('color');              
            colors.style.backgroundColor = color;
    }       
</script>

<style type = "text/CSS">
    <!--
    #color {
        background-color: yellow;
    }
    -->
</style>

<div id="color" style="border-color: #eee; border-style: solid; width: 300px; height: 300px; margin-right: auto; margin-left: auto; margin-top: 200px; padding: 50px; background-color: yellow;" onChange = "readColor ();">
    Aici are loc lupta
</div>  
<div style="text-align: center; margin-top: 20px;"> 
    <input type="button" name="Change color" value="Change Color" onClick = "changeColor ()">
</div>

Answer 1

I believe just changing

var colorArray = {yellow, red, blue, purple};

to

var colorArray = ['yellow', 'red', 'blue', 'purple'];

should do it..

Demo at http://jsfiddle.net/pYc4P/

Answer 2

I think the problem is that you are not passing in color on the onclick

Should it not read:

<input type="button" 
       name="Change color" 
       value="Change Color" 
       onClick = "changeColor (color)">

Answer 3

You create colorArray as an object, but you are using it as an array.

Try declaring it as an array instead:

var colorArray = new Array("yellow", "red", "blue", "purple");

Or:

var colorArray = ["yellow", "red", "blue", "purple"];