常用的String原型

对于常用的字符串原型的举例

 在字符串末尾追加字符串 
string.prototype.append = function (str) {
return this.concat(str);
}

 删除指定索引位置的字符，索引无效将不删除任何字符 
string.prototype.deletecharat = function (index) {
if (index < 0 || index >= this.length) {
return this.valueof();
}
else if (index == 0) {
return this.substring(1, this.length);
}
else if (index == this.length - 1) {
return this.substring(0, this.length - 1);
}
else {
return this.substring(0, index) + this.substring(index + 1);
}
}
 删除指定索引区间的字符串 
string.prototype.deletestring = function (start, end) {
if (start == end) {
return this.deletecharat(start);
}
else {
if (start > end) {
var temp = start;
start = end;
end = temp;
}
if (start < 0) {
start = 0;
}
if (end > this.length - 1) {
end = this.length - 1;
}
return this.substring(0, start) + this.substring(end +1 , this.length);
}
}
 检查字符串是否以substr结尾 
string.prototype.endwith = function (substr) {
if (substr.length > this.length) {
return false;
}
else {
return (this.lastindexof(substr) == (this.length - substr.length)) ? true : false;
}
}
 比较两个字符串是否相等，也可以直接用 == 进行比较 
string.prototype.equal = function (str) {
if (this.length != str.length) {
return false;
}
else {
for (var i = 0; i < this.length; i++) {
if (this.charat(i) != str.charat(i)) {
return false;
}
}
return true;
}
}
 比较两个字符串是否相等，不区分大小写 
string.prototype.equalignorecase = function (str) {
var temp1 = this.tolowercase();
var temp2 = str.tolowercase();
return temp1.equal(temp2);
}
 将指定的字符串插入到指定的位置后面，索引无效将直接追加到字符串的末尾 
string.prototype.insert = function (ofset, substr) {
if (ofset < 0 || ofset >= this.length - 1) {
return this.append(substr);
}
return this.substring(0, ofset + 1) + substr + this.substring(ofset + 1);
}
 判断字符串是否数字串 
string.prototype.isallnumber = function () {
for (var i = 0; i < this.length; i++) {
if (this.charat(i) < '0' || this.charat(i) > '9') {
return false;
}
}
return true;
}
 将字符串反序排列 
string.prototype.reserve = function () {
var temp = "";
for (var i = this.length - 1; i >= 0; i--) {
temp = temp.concat(this.charat(i));
}
return temp;
}
 将指定的位置的字符设置为另外指定的字符或字符串.索引无效将直接返回不做任何处理 
string.prototype.setcharat = function (index, substr) {
if (index < 0 || index > this.length - 1) {
return this.valueof();
}
return this.substring(0, index) + substr + this.substring(index+1);
}
 检查字符串是否以substr开头 
string.prototype.startwith = function (substr) {
if (substr.length > this.length) {
return false;
}
return (this.indexof(substr) == 0) ? true : false;
}
 计算长度，每个汉字占两个长度，英文字符每个占一个长度 
string.prototype.charlength = function () {
var temp = 0;
for (var i = 0; i < this.length; i++) {
if (this.charcodeat(i) > 255) {
temp += 2;
}
else {
temp += 1;
}
}
return temp;
}
string.prototype.charlengthreg = function () {
return this.replace(/[^\x00-\xff]/g, "**").length;
}
 去掉首尾空格 
string.prototype.trim = function () {
return this.replace(/(^\s*)|(\s*$)/g, "");
}
 测试是否是数字 
string.prototype.isnumeric = function () {
var tmpfloat = parsefloat(this);
if (isnan(tmpfloat))
return false;
var tmplen = this.length - tmpfloat.tostring().length;
return tmpfloat + "0".repeat(tmplen) == this;
}
 测试是否是整数 
string.prototype.isint = function () {
if (this == "nan")
return false;
return this == parseint(this).tostring();
}
 获取n个相同的字符串 
string.prototype.repeat = function (num) {
var tmparr = [];
for (var i = 0; i < num; i++) tmparr.push(this);
return tmparr.join("");
}
 除去左边空白  
string.prototype.ltrim = function () {
return this.replace(/^s+/g, "");
}
 除去右边空白 
string.prototype.rtrim = function () {
return this.replace(/s+$/g, "");
}
 除去两边空白  
string.prototype.trim = function () {
return this.replace(/(^s+)|(s+$)/g, "");
}
 保留数字 
string.prototype.getnum = function () {
return this.replace(/[^d]/g, "");
}
 保留字母 
string.prototype.geten = function () {
return this.replace(/[^a-za-z]/g, "");
}
 保留中文
string.prototype.getcn = function () {
return this.replace(/[^u4e00-u9fa5uf900-ufa2d]/g, "");
}
 得到字节长度 
string.prototype.getreallength = function () {
return this.replace(/[^x00-xff]/g, "--").length;
}
 从左截取指定长度的字串 
string.prototype.left = function (n) {
return this.slice(0, n);
}
 从右截取指定长度的字串  
string.prototype.right = function (n) {
return this.slice(this.length - n);
}
 删除首尾空格  
string.prototype.trim = function() {
return this.replace(/(^\s*)|(\s*$)/g, "");
}

 统计指定字符出现的次数  
string.prototype.occurs = function(ch) {
// var re = eval("/[^"+ch+"]/g");
// return this.replace(re, "").length;
return this.split(ch).length-1;
}

 检查是否由数字组成 
string.prototype.isdigit = function() {
var s = this.trim();
return (s.replace(/\d/g, "").length == 0);
}

 检查是否由数字字母和下划线组成 
string.prototype.isalpha = function() {
return (this.replace(/\w/g, "").length == 0);
}

检查是否为数 
string.prototype.isnumber = function() {
var s = this.trim();
return (s.search(/^[+-]?[0-9.]*$/) >= 0);
}

返回字节数
string.prototype.lenb = function() {
return this.replace(/[^\x00-\xff]/g,"**").length;
}

检查是否包含汉字
string.prototype.isinchinese = function() {
return (this.length != this.replace(/[^\x00-\xff]/g,"**").length);
}

简单的email检查 
string.prototype.isemail = function() {
　var strr;
var mail = this;
　var re = /(\w+@\w+\.\w+)(\.{0,1}\w*)(\.{0,1}\w*)/i;
　re.exec(mail);
　if(regexp.$3!="" && regexp.$3!="." && regexp.$2!=".")
strr = regexp.$1+regexp.$2+regexp.$3;
　else
　　if(regexp.$2!="" && regexp.$2!=".")
strr = regexp.$1+regexp.$2;
　　else
　strr = regexp.$1;
　return (strr==mail);
}

简单的日期检查，成功返回日期对象  
string.prototype.isdate = function() {
var p;
var re1 = /(\d{4})[年./-](\d{1,2})[月./-](\d{1,2})[日]?$/;
var re2 = /(\d{1,2})[月./-](\d{1,2})[日./-](\d{2})[年]?$/;
var re3 = /(\d{1,2})[月./-](\d{1,2})[日./-](\d{4})[年]?$/;
if(re1.test(this)) {
p = re1.exec(this);
return new date(p[1],p[2],p[3]);
}
if(re2.test(this)) {
p = re2.exec(this);
return new date(p[3],p[1],p[2]);
}
if(re3.test(this)) {
p = re3.exec(this);
return new date(p[3],p[1],p[2]);
}
return false;
}

检查是否有列表中的字符字符
string.prototype.isinlist = function(list) {
var re = eval("/["+list+"]/");
return re.test(this);
}

系统中js的扩展函数 

/清除两边的空格
string.prototype.trim = function() {
return this.replace(/(^\s*)|(\s*$)/g, '');
};
 合并多个空白为一个空白
string.prototype.resetblank = function() {
var regex = /\s+/g;
return this.replace(regex, ' ');
};

保留数字
string.prototype.getnum = function() {
var regex = /[^\d]/g;
return this.replace(regex, '');
};

保留中文
string.prototype.getcn = function() {
var regex = /[^\u4e00-\u9fa5\uf900-\ufa2d]/g;
return this.replace(regex, '');
};

string转化为number
string.prototype.toint = function() {
return isnan(parseint(this)) ? this.tostring() : parseint(this);
};

 得到字节长度
string.prototype.getlen = function() {
var regex = /^[\u4e00-\u9fa5\uf900-\ufa2d]+$/;
if (regex.test(this)) {
return this.length * 2;
} else {
var omatches = this.match(/[\x00-\xff]/g);
var olength = this.length * 2 - omatches.length;
return olength;
}
};

 获取文件全名
string.prototype.getfilename = function() {
var regex = /^.*\/([^\/\?]*).*$/;
return this.replace(regex, '$1');
};

 数字补零
number.prototype.lenwithzero = function(ocount) {
var strtext = this.tostring();
while (strtext.length < ocount) {
strtext = '0' + strtext;
}
return strtext;
};

unicode还原
number.prototype.chrw = function() {
return string.fromcharcode(this);
};

 数字数组由小到大排序
array.prototype.min2max = function() {
var ovalue;
for (var i = 0; i < this.length; i++) {
for (var j = 0; j <= i; j++) {
if (this[i] < this[j]) {
ovalue = this[i];
this[i] = this[j];
this[j] = ovalue;
}
}
}
return this;
};

 数字数组由大到小排序
array.prototype.max2min = function() {
var ovalue;
for (var i = 0; i < this.length; i++) {
for (var j = 0; j <= i; j++) {
if (this[i] > this[j]) {
ovalue = this[i];
this[i] = this[j];
this[j] = ovalue;
}
}
}
return this;
};

 获得数字数组中最大项
array.prototype.getmax = function() {
var ovalue = 0;
for (var i = 0; i < this.length; i++) {
if (this[i] > ovalue) {
ovalue = this[i];
}
}
return ovalue;
};

 获得数字数组中最小项
array.prototype.getmin = function() {
var ovalue = 0;
for (var i = 0; i < this.length; i++) {
if (this[i] < ovalue) {
ovalue = this[i];
}
}
return ovalue;
};

 获取当前时间的中文形式
date.prototype.getcndate = function() {
var odatetext = '';
odatetext += this.getfullyear().lenwithzero(4) + new number(24180).chrw();
odatetext += this.getmonth().lenwithzero(2) + new number(26376).chrw();
odatetext += this.getdate().lenwithzero(2) + new number(26085).chrw();
odatetext += this.gethours().lenwithzero(2) + new number(26102).chrw();
odatetext += this.getminutes().lenwithzero(2) + new number(20998).chrw();
odatetext += this.getseconds().lenwithzero(2) + new number(31186).chrw();
odatetext += new number(32).chrw() + new number(32).chrw() + new number(26143).chrw() + new number(26399).chrw() + new string('26085199682010819977222352011620845').substr(this.getday() * 5, 5).toint().chrw();
return odatetext;
};
扩展date格式化
date.prototype.format = function(format) {
var o = {
"m+": this.getmonth() + 1, //月份
"d+": this.getdate(), //日
"h+": this.gethours() % 12 == 0 ? 12 : this.gethours() % 12, //小时
"h+": this.gethours(), //小时
"m+": this.getminutes(), //分
"s+": this.getseconds(), //秒
"q+": math.floor((this.getmonth() + 3) / 3), //季度
"s": this.getmilliseconds() //毫秒
};
var week = {
"0": "\u65e5",
"1": "\u4e00",
"2": "\u4e8c",
"3": "\u4e09",
"4": "\u56db",
"5": "\u4e94",
"6": "\u516d"
};
if (/(y+)/.test(format)) {
format = format.replace(regexp.$1, (this.getfullyear() + "").substr(4 - regexp.$1.length));
}
if (/(e+)/.test(format)) {
format = format.replace(regexp.$1, ((regexp.$1.length > 1) ? (regexp.$1.length > 2 ? "\u661f\u671f" : "\u5468") : "") + week[this.getday() + ""]);
}
for (var k in o) {
if (new regexp("(" + k + ")").test(format)) {
format = format.replace(regexp.$1, (regexp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
}
}
return format;
}
date.prototype.diff = function(interval, objdate) {
 若参数不足或 objdate 不是日期类型則回传 undefined
if (arguments.length < 2 || objdate.constructor != date) { return undefined; }
switch (interval) {
//计算秒差
case 's': return parseint((objdate - this) / 1000);
//计算分差
case 'n': return parseint((objdate - this) / 60000);
//计算時差
case 'h': return parseint((objdate - this) / 3600000);
//计算日差
case 'd': return parseint((objdate - this) / 86400000);
//计算周差
case 'w': return parseint((objdate - this) / (86400000 * 7));
//计算月差
case 'm': return (objdate.getmonth() + 1) + ((objdate.getfullyear() - this.getfullyear()) * 12) - (this.getmonth() + 1);
//计算年差
case 'y': return objdate.getfullyear() - this.getfullyear();
//输入有误
default: return undefined;
}
};

 检测是否为空
object.prototype.isnullorempty = function() {
var obj = this;
var flag = false;
if (obj == null || obj == undefined || typeof (obj) == 'undefined' || obj == '') {
flag = true;
} else if (typeof (obj) == 'string') {
obj = obj.trim();
if (obj == '') {//为空
flag = true;
} else {//不为空
obj = obj.touppercase();
if (obj == 'null' || obj == 'undefined' || obj == '{}') {
flag = true;
}
}
}
else {
flag = false;
}
return flag;
};