The source code

    /**
     * @class Ext.util.Format
     * Reusable data formatting functions
     * @singleton
     */
    Ext.util.Format = function() {
        var trimRe         = /^\s+|\s+$/g,
            stripTagsRE    = /<\/?[^>]+>/gi,
            stripScriptsRe = /(?:<script.*?>)((\n|\r|.)*?)(?:<\/script>)/ig,
            nl2brRe        = /\r?\n/g;

        return {
            /**
             * Truncate a string and add an ellipsis ('...') to the end if it exceeds the specified length
             * @param {String} value The string to truncate
             * @param {Number} length The maximum length to allow before truncating
             * @param {Boolean} word True to try to find a common work break
             * @return {String} The converted text
             */
            ellipsis : function(value, len, word) {
                if (value && value.length > len) {
                    if (word) {
                        var vs    = value.substr(0, len - 2),
                            index = Math.max(vs.lastIndexOf(' '), vs.lastIndexOf('.'), vs.lastIndexOf('!'), vs.lastIndexOf('?'));
                        if (index == -1 || index < (len - 15)) {
                            return value.substr(0, len - 3) + "...";
                        } else {
                            return vs.substr(0, index) + "...";
                        }
                    } else {
                        return value.substr(0, len - 3) + "...";
                    }
                }
                return value;
            },

            /**
             * Checks a reference and converts it to empty string if it is undefined
             * @param {Mixed} value Reference to check
             * @return {Mixed} Empty string if converted, otherwise the original value
             */
            undef : function(value) {
                return value !== undefined ? value : "";
            },

            /**
             * Checks a reference and converts it to the default value if it's empty
             * @param {Mixed} value Reference to check
             * @param {String} defaultValue The value to insert if it's undefined (defaults to "")
             * @return {String}
             */
            defaultValue : function(value, defaultValue) {
                if (!defaultValue && defaultValue !== 0) {
                    defaultValue = '';
                }
                return value !== undefined && value !== '' ? value : defaultValue;
            },

            /**
             * Convert certain characters (&, <, >, and ') to their HTML character equivalents for literal display in web pages.
             * @param {String} value The string to encode
             * @return {String} The encoded text
             */
            htmlEncode : function(value) {
                return !value ? value : String(value).replace(/&/g, "&amp;").replace(/>/g, "&gt;").replace(/</g, "&lt;").replace(/"/g, "&quot;");
            },

            /**
             * Convert certain characters (&, <, >, and ') from their HTML character equivalents.
             * @param {String} value The string to decode
             * @return {String} The decoded text
             */
            htmlDecode : function(value) {
                return !value ? value : String(value).replace(/&gt;/g, ">").replace(/&lt;/g, "<").replace(/&quot;/g, '"').replace(/&amp;/g, "&");
            },

            /**
             * Trims any whitespace from either side of a string
             * @param {String} value The text to trim
             * @return {String} The trimmed text
             */
            trim : function(value) {
                return String(value).replace(trimRe, "");
            },

            /**
             * Returns a substring from within an original string
             * @param {String} value The original text
             * @param {Number} start The start index of the substring
             * @param {Number} length The length of the substring
             * @return {String} The substring
             */
            substr : function(value, start, length) {
                return String(value).substr(start, length);
            },

            /**
             * Converts a string to all lower case letters
             * @param {String} value The text to convert
             * @return {String} The converted text
             */
            lowercase : function(value) {
                return String(value).toLowerCase();
            },

            /**
             * Converts a string to all upper case letters
             * @param {String} value The text to convert
             * @return {String} The converted text
             */
            uppercase : function(value) {
                return String(value).toUpperCase();
            },

            /**
             * Converts the first character only of a string to upper case
             * @param {String} value The text to convert
             * @return {String} The converted text
             */
            capitalize : function(value) {
                return !value ? value : value.charAt(0).toUpperCase() + value.substr(1).toLowerCase();
            },

            // private
            call : function(value, fn) {
                if (arguments.length > 2) {
                    var args = Array.prototype.slice.call(arguments, 2);
                    args.unshift(value);
                    return eval(fn).apply(window, args);
                } else {
                    return eval(fn).call(window, value);
                }
            },

            /**
             * Format a number as US currency
             * @param {Number/String} value The numeric value to format
             * @return {String} The formatted currency string
             */
            usMoney : function(v) {
                v = (Math.round((v-0)*100))/100;
                v = (v == Math.floor(v)) ? v + ".00" : ((v*10 == Math.floor(v*10)) ? v + "0" : v);
                v = String(v);
                var ps = v.split('.'),
                    whole = ps[0],
                    sub = ps[1] ? '.'+ ps[1] : '.00',
                    r = /(\d+)(\d{3})/;
                while (r.test(whole)) {
                    whole = whole.replace(r, '$1' + ',' + '$2');
                }
                v = whole + sub;
                if (v.charAt(0) == '-') {
                    return '-$' + v.substr(1);
                }
                return "$" +  v;
            },

            /**
             * Parse a value into a formatted date using the specified format pattern.
             * @param {String/Date} value The value to format (Strings must conform to the format expected by the javascript Date object's <a href="http://www.w3schools.com/jsref/jsref_parse.asp">parse()</a> method)
             * @param {String} format (optional) Any valid date format string (defaults to 'm/d/Y')
             * @return {String} The formatted date string
             */
            date : function(v, format) {
                if (!v) {
                    return "";
                }
                if (!Ext.isDate(v)) {
                    v = new Date(Date.parse(v));
                }
                return v.dateFormat(format || "m/d/Y");
            },

            /**
             * Returns a date rendering function that can be reused to apply a date format multiple times efficiently
             * @param {String} format Any valid date format string
             * @return {Function} The date formatting function
             */
            dateRenderer : function(format) {
                return function(v) {
                    return Ext.util.Format.date(v, format);
                };
            },

            /**
             * Strips all HTML tags
             * @param {Mixed} value The text from which to strip tags
             * @return {String} The stripped text
             */
            stripTags : function(v) {
                return !v ? v : String(v).replace(stripTagsRE, "");
            },

            /**
             * Strips all script tags
             * @param {Mixed} value The text from which to strip script tags
             * @return {String} The stripped text
             */
            stripScripts : function(v) {
                return !v ? v : String(v).replace(stripScriptsRe, "");
            },

            /**
             * Simple format for a file size (xxx bytes, xxx KB, xxx MB)
             * @param {Number/String} size The numeric value to format
             * @return {String} The formatted file size
             */
            fileSize : function(size) {
                if (size < 1024) {
                    return size + " bytes";
                } else if (size < 1048576) {
                    return (Math.round(((size*10) / 1024))/10) + " KB";
                } else {
                    return (Math.round(((size*10) / 1048576))/10) + " MB";
                }
            },

            /**
             * It does simple math for use in a template, for example:<pre><code>
             * var tpl = new Ext.Template('{value} * 10 = {value:math("* 10")}');
             * </code></pre>
             * @return {Function} A function that operates on the passed value.
             */
            math : function(){
                var fns = {};

                return function(v, a){
                    if (!fns[a]) {
                        fns[a] = new Function('v', 'return v ' + a + ';');
                    }
                    return fns[a](v);
                };
            }(),

            /**
             * Rounds the passed number to the required decimal precision.
             * @param {Number/String} value The numeric value to round.
             * @param {Number} precision The number of decimal places to which to round the first parameter's value.
             * @return {Number} The rounded value.
             */
            round : function(value, precision) {
                var result = Number(value);
                if (typeof precision == 'number') {
                    precision = Math.pow(10, precision);
                    result = Math.round(value * precision) / precision;
                }
                return result;
            },

            /**
             * Formats the number according to the format string.
             * <div style="margin-left:40px">examples (123456.789):
             * <div style="margin-left:10px">
             * 0 - (123456) show only digits, no precision<br>
             * 0.00 - (123456.78) show only digits, 2 precision<br>
             * 0.0000 - (123456.7890) show only digits, 4 precision<br>
             * 0,000 - (123,456) show comma and digits, no precision<br>
             * 0,000.00 - (123,456.78) show comma and digits, 2 precision<br>
             * 0,0.00 - (123,456.78) shortcut method, show comma and digits, 2 precision<br>
             * To reverse the grouping (,) and decimal (.) for international numbers, add /i to the end.
             * For example: 0.000,00/i
             * </div></div>
             * @param {Number} v The number to format.
             * @param {String} format The way you would like to format this text.
             * @return {String} The formatted number.
             */
            number: function(v, format) {
                if (!format) {
                    return v;
                }
                v = Ext.num(v, NaN);
                if (isNaN(v)) {
                    return '';
                }
                var comma = ',',
                    dec   = '.',
                    i18n  = false,
                    neg   = v < 0;

                v = Math.abs(v);
                if (format.substr(format.length - 2) == '/i') {
                    format = format.substr(0, format.length - 2);
                    i18n   = true;
                    comma  = '.';
                    dec    = ',';
                }

                var hasComma = format.indexOf(comma) != -1,
                    psplit   = (i18n ? format.replace(/[^\d\,]/g, '') : format.replace(/[^\d\.]/g, '')).split(dec);

                if (1 < psplit.length) {
                    v = v.toFixed(psplit[1].length);
                } else if(2 < psplit.length) {
                    throw ('NumberFormatException: invalid format, formats should have no more than 1 period: ' + format);
                } else {
                    v = v.toFixed(0);
                }

                var fnum = v.toString();

                psplit = fnum.split('.');

                if (hasComma) {
                    var cnum = psplit[0],
                        parr = [],
                        j    = cnum.length,
                        m    = Math.floor(j / 3),
                        n    = cnum.length % 3 || 3,
                        i;

                    for (i = 0; i < j; i += n) {
                        if (i != 0) {
                            n = 3;
                        }

                        parr[parr.length] = cnum.substr(i, n);
                        m -= 1;
                    }
                    fnum = parr.join(comma);
                    if (psplit[1]) {
                        fnum += dec + psplit[1];
                    }
                } else {
                    if (psplit[1]) {
                        fnum = psplit[0] + dec + psplit[1];
                    }
                }

                return (neg ? '-' : '') + format.replace(/[\d,?\.?]+/, fnum);
            },

            /**
             * Returns a number rendering function that can be reused to apply a number format multiple times efficiently
             * @param {String} format Any valid number format string for {@link #number}
             * @return {Function} The number formatting function
             */
            numberRenderer : function(format) {
                return function(v) {
                    return Ext.util.Format.number(v, format);
                };
            },

            /**
             * Selectively do a plural form of a word based on a numeric value. For example, in a template,
             * {commentCount:plural("Comment")}  would result in "1 Comment" if commentCount was 1 or would be "x Comments"
             * if the value is 0 or greater than 1.
             * @param {Number} value The value to compare against
             * @param {String} singular The singular form of the word
             * @param {String} plural (optional) The plural form of the word (defaults to the singular with an "s")
             */
            plural : function(v, s, p) {
                return v +' ' + (v == 1 ? s : (p ? p : s+'s'));
            },

            /**
             * Converts newline characters to the HTML tag &lt;br/>
             * @param {String} The string value to format.
             * @return {String} The string with embedded &lt;br/> tags in place of newlines.
             */
            nl2br : function(v) {
                return Ext.isEmpty(v) ? '' : v.replace(nl2brRe, '<br/>');
            }
        };
    }();