static/ext/src/Ext-more.js
function(items, connector) {
            var length = items.length,
                head,
                tail;

            if (length <= 1) {
                return items[0];
            } else {
                head = items.slice(0, length - 1);
                tail = items[length - 1];

                return Ext.util.Format.format("{0} {1} {2}", head.join(", "), connector || 'and', tail);
            }
        }
function(items, connector) {
            var length = items.length,
                head,
                tail;

            if (length <= 1) {
                return items[0];
            } else {
                head = items.slice(0, length - 1);
                tail = items[length - 1];

                return Ext.util.Format.format("{0} {1} {2}", head.join(", "), connector || 'and', tail);
            }
        }
Turns an array into a sentence, joined by a specified connector - e.g.:

Ext.toSentence(['Adama', 'Tigh', 'Roslin']); //'Adama, Tigh and Roslin'
Ext.toSentence(['Adama', 'Tigh', 'Roslin'], 'or'); //'Adama, Tigh or Roslin'

@param {String[]} items The array to create a sentence from
@param {String} connector The string to use to connect the last two words.
Usually 'and' or 'or' - defaults to 'and'.
@return {String} The sentence string
@deprecated 4.0.0 Will be removed in the next major version