Stringify list of numbers into a number-range like in a book

rangeToString.js

/**
 * Originally from: https://stackoverflow.com/a/24104156
 * Rewritten in JavaScript
 */
var pagenumbers = [
    10,12,13,45,46,47,48,49,50,3,4,5
];

function rangeToString(items) {
    items.sort(function (a, b) {
        return a - b;
    });
    var point = null;
    var range = false;
    var string = '';
    for (var i = 0; i < items.length; i++) {
        if (point === items[i]) {
            continue;
        }
        if (point === null) {
            string = string + items[i];
        } else if ((point + 1) === items[i]) {
            range = true;
        } else {
            if (range === true) {
                string = string + '-' + point;
            }
            string = string + ',' + items[i];
        }
        point = items[i];
    }
    if (range === true) {
        string = string + '-' + point;
    }

    return string;
}

var string = rangeToString(pagenumbers);