JS字符串函数扩展代码

代码如下:
/****************************************************
*CreateBy:joe zhou
*CreateDate:2011-9-4
*Description:字符串辅助函数
****************************************************/
//String.prototype = {
// caption: function () {
// },
// leftPad: function (padChar, width) {
// if (this.length >= width) {
// return this;
// }
// }
//};
String.prototype.padLeft = function (padChar, width) {
var ret = this;
while (ret.length < width) {
if (ret.length + padChar.length < width) {
ret = padChar + ret;
}
else {
ret = padChar.substring(0, width-ret.length) + ret;
}
}
return ret;
};
String.prototype.padRight = function (padChar, width) {
var ret = this;
while (ret.length < width) {
if (ret.length + padChar.length < width) {
ret += padChar;
}
else {
ret += padChar.substring(0, width - ret.length);
}
}
return ret;
};
String.prototype.trim = function () {
return this.replace(/^\s+/, '').replace(/\s+$/, '');
};
String.prototype.trimLeft = function () {
return this.replace(/^\s+/, '');
};
String.prototype.trimRight = function () {
return this.replace(/\s+$/, '');
};
String.prototype.caption = function () {
if (this) {
return this.charAt(0).toUpperCase() + this.substr(1);
}
return this;
};
String.prototype.reverse = function () {
var ret = '';
for (var i = this.length - 1; i >= 0; i--) {
ret += this.charAt(i);
}
return ret;
};
String.prototype.startWith = function (compareValue, ignoreCase) {
if (ignoreCase) {
return this.toLowerCase().indexOf(compareValue.toLowerCase()) == 0;
}
return this.indexOf(compareValue) == 0
};
String.prototype.endWith = function (compareValue, ignoreCase) {
if (ignoreCase) {
return this.toLowerCase().lastIndexOf(compareValue.toLowerCase()) == this.length - compareValue.length;
}
return this.lastIndexOf(compareValue) == this.length - compareValue.length;
};

js字符串 扩展 函数 js