hex code for no color in colorField

I am using granite colorField and i have allowed no color option in its swatch. the title value pair for no color is :

the value is empty

In my js file, I need to check if no color option is selected. but the below code doesnt work:

selector: "[xyz]",
validate: function(el) {
var input = el.value;

if(input != "" && input != ''){

//task

}

whereas if I check using some hex code for color, then the if condition works fine. What is the code/way to check no color? I am using acs commons generic list to get color options