Default Settings Pattern

gistfile1.txt

var defaultSettings = {
    x:0.5,
    y:true,
}
var settings = defaultSettings;

function exampleFunction(userSettings) {
    //extend settings object
    for (var key in userSettings) {
        if (userSettings.hasOwnProperty(key) && userSettings[key] !== undefined) {
            settings[key] = userSettings[key];
        }
    }
}