Prototypes String to allow for any string to be capitalized. Can also take into account English articles by using the 'title' type. Warning: automatically lower cases the entire string, so words like "McDonald's" will be out put as "Mcdonald's". See bottom of Gist for usage examples

capitalize.js

String.prototype.capitalize = function(type) {
      var  str = this.toLowerCase();

    if (type) {
        var nArr = [],
            articles	= ["a", "an", "and", "as", "at", "but", "by", "etc", "for", "in", "into", "is", "nor", "of", "off", "on", "onto", "or", "so", "the", "to", "unto", "via"],
            arr = str.split(' '),
            i = 0,
            value;
        for (i; i < arr.length; i++) {
            value = arr[i];
            if (i == 0 || i == arr.length - 1 || type == 'all' || (type == 'title' && articles.indexOf(value) < 0)) {
                nArr.push(value.charAt(0).toUpperCase() + value.slice(1));
            }
            else {
                nArr.push(value);
            }
        }
        return nArr.join(' ');
    }
    return str.charAt(0).toUpperCase() + str.slice(1);
}

"ThiS sHoulD Be PROPERLY capitalized and all the if and or end capital articleS Should NOT BE".capitalize('title');
// output: "This Should Be Properly Capitalized and All the If and or End Capital Articles Should Not Be"

"ThiS sHoulD Be PROPERLY capitalized and all the if and or end capital articleS Should NOT BE".capitalize('all');
// output: "This Should Be Properly Capitalized And All The If And Or End Capital Articles Should Not Be"

"ThiS sHoulD Be PROPERLY capitalized and all the if and or end capital articleS Should NOT BE".capitalize();
//output: "This should be properly capitalized and all the if and or end capital articles should not be"