JavaScript Guessing Game

JavaScript

var target;
var guess_input;
var guesses = 0;
var finished = false;
var colors = ["aqua", "black", "blue", "cyan", "green", "violet", "white", "yellow"];

function do_game() {
    var random_number = Math.random() * 8;
    var random_number_integer = Math.floor(random_number);
    target = colors[random_number_integer];
    alert(target);
    while (!finished) {
        guess_input = prompt("I am thinking of one of these colors: \n\n" +
            "aqua, black, blue, cyan, green, violet, white, yellow \n\n" +
            "What color am I thinking of?");
        guesses += 1;
        if (guess_input == target) finished = true;
    }
}

window.onload = do_game();