对Textbox的值转换为带千位符和小数的Decimal字符串

以下Function可以用于textbox的KeyUp事件:

2014-06-06 发现旧版IE不支持selectionStart还有字符串的"[]"索引获取值, 已经修复这个bug.

2014-06-10 修复上一次修复遗留的IE的bug.

/*
Validate the textbox value is decimal.
*/

var numberChars = "1234567890";

function isDecimal(item) {
    var obj = $(item);
    if (obj.length > 0) {
        if ($(obj).val() != null && typeof ($(obj).val()) != 'undefined') {

            var str = $(obj).val().toString();
            if (str != "") {
                //记录初始光标位置
                var selectionStart = item.selectionStart;
                //兼容IE
                if (typeof (item.createTextRange) != "undefined") {
                    item.focus();
                    var r = document.selection.createRange(), tr = item.createTextRange();
                    tr.setEndPoint('endtoend', r);
                    item.selectionStart = tr.text.length - r.text.length;
                    item.selectionEnd = tr.text.length;
                    selectionStart = item.selectionStart;
                }
                //用于判断千位符的数量变化
                var pren = str.split(',').length - 1;
                //合法Decimal格式字符串, 可以含千位符(,号)
                var pattern = '^-?0(\\.\\d+)?$|^-?[1-9]\\d*(\\.\\d+)?$|^-?([1-9][0-9]{0,2},)(\\d{3},)*(\\d{3})(\\.\\d+)?$';
                //合法字符集, 不包括,号
                var pattern2 = '^[0-9\.-]*$';

                var reg = new RegExp(pattern, 'g');
                var reg2 = new RegExp(pattern2, 'g');

                //转换之前, 去除,号
                var temp = str.replace(/,/, "");
                while (temp.indexOf(',') >= 0) {
                    temp = temp.replace(/,/, "");
                }
                var nstr = '';
                if (reg2.test(temp)) {
                    //除(/)数和模(%)数
                    var k1 = 0, k2 = 0;
                    //转换开始和结束位置
                    var start = 0, end = 0;
                    //千位符(,号)
                    var pp = ',';
                    //计数(3的倍数)
                    var p = 0;
                    //判断前置的非数字符号(这里是-号)
                    for (; start < temp.length; start++) {
                        if (numberChars.indexOf(temp.substring(start, start + 1)) >= 0) {
                            break;
                        }
                        nstr = nstr.concat(temp.substring(start, start + 1));
                    }
                    //小数符号(.号)的位置
                    var pIndex = temp.indexOf('.');
                    //存在小数符(.号), 即以它的位置为结束位置, 否则以字符串结尾为结束位置
                    if (pIndex >= 0) {
                        end = pIndex;
                    } else {
                        end = temp.length;
                    }
                    k2 = (end - start) % 3;
                    k1 = parseInt((end - start) / 3);

                    for (var i = 0; i < k2; i++) {
                        nstr = nstr.concat(temp.substring(start + i, start + i + 1));
                    }
                    if (k1 > 0 && k2 > 0) {
                        nstr = nstr.concat(pp);
                    }
                    for (var i = k2 + start; i < end; i++) {
                        nstr = nstr.concat(temp.substring(i, i + 1));
                        p++;
                        if (p == 3 && i + 1 != end) {
                            p = 0;
                            nstr = nstr.concat(pp);
                        }
                    }
                    for (var i = end; i < temp.length; i++) {
                        nstr = nstr.concat(temp.substring(i, i + 1));
                    }
                } else {
                    nstr = str;
                }
                if (!reg.test(nstr)) {
                    //去除不合法符号(包括手动输入的,号)
                    if (nstr.match(/[^0-9,\.-]/g) != null) {
                        var matchLength = nstr.match(/[^0-9,\.-]/g).length;
                        if (matchLength > 0) {
                            var tempLength = nstr.length;
                            nstr = nstr.replace(/[^0-9,\.-]/g, '');
                            $(item).val(nstr);
                            selectionStart = selectionStart - tempLength + nstr.length;
                        }
                    }
                }
                $(item).val(nstr);
                if (str != nstr) {
                    var tpren = nstr.split(',').length - 1;
                    if (pren != tpren) { //根据千位符的数量变化, 控制光标位置
                        item.selectionStart = selectionStart + tpren - pren;
                        item.selectionEnd = selectionStart + tpren - pren;
                    } else {
                        item.selectionStart = selectionStart;
                        item.selectionEnd = selectionStart;
                    }
                }
                //兼容IE
                if (typeof (item.createTextRange) != "undefined") {
                    var range = item.createTextRange();
                    range.collapse(true);
                    range.moveEnd('character', item.selectionEnd);
                    range.moveStart('character', item.selectionStart);
                    range.select();
                }
                return true;
            }
        }
    }
    return false;
}