Replace spaces with dashes and make all letters lower-case

Just use the String replace and toLowerCase methods, for example:

var str = "Sonic Free Games";
str = str.replace(/\s+/g, '-').toLowerCase();
console.log(str); // "sonic-free-games"

Notice the g flag on the RegExp, it will make the replacement globally within the string, if it's not used, only the first occurrence will be replaced, and also, that RegExp will match one or more white-space characters.

Above answer can be considered to be confusing a little. String methods are not modifying original object. They return new object. It must be:

var str = "Sonic Free Games";
str = str.replace(/\s+/g, '-').toLowerCase(); //new object assigned to var str

You can also use split and join:

"Sonic Free Games".split(" ").join("-").toLowerCase(); //sonic-free-games