I have the following code below that I'm trying to set a background color. However, the background color returns as an empty string. I'm not sure why...Does it have something to do with javascript types?

```
function function1(){
var color = document.getElementById('rg_vw.national_avg').style.backgroundColor;
//this below appears as an empty alert at runtime. it's an empty string. 
alert(color)
}

```

Just as a sanity check, if I use the 'value' property, it prints out the correct value for that particular field...so I'm just a bit frustrated as to why the backgroundColor is an empty string.

```
//this works just fine
var value = document.getElementById('rg_vw.national_avg').value
alert(value)   

```