JS字符串函数扩展

 1 /****************************************************
 2 *CreateBy:joe zhou
 3 *CreateDate:2011-9-4
 4 *Description:字符串辅助函数
 5 ****************************************************/
 6 //String.prototype = {
 7 //    caption: function () {
 8 
 9 //    },
10 //    leftPad: function (padChar, width) {
11 //        if (this.length >= width) {
12 //            return this;
13 //        }
14 //    }
15 //};
16 
17 String.prototype.padLeft = function (padChar, width) {
18     var ret = this;
19     while (ret.length < width) {
20         if (ret.length + padChar.length < width) {
21             ret = padChar + ret;
22         }
23         else {
24             ret = padChar.substring(0, width-ret.length) + ret;
25         }
26     }
27     return ret;
28 };
29 
30 String.prototype.padRight = function (padChar, width) {
31     var ret = this;
32     while (ret.length < width) {
33         if (ret.length + padChar.length < width) {
34             ret += padChar;
35         }
36         else {
37             ret += padChar.substring(0, width - ret.length);
38         }
39     }
40     return ret;
41 };
42 
43 String.prototype.trim = function () {
44     return this.replace(/^\s+/, '').replace(/\s+$/, '');
45 };
46 
47 String.prototype.trimLeft = function () {
48     return this.replace(/^\s+/, '');
49 };
50 
51 String.prototype.trimRight = function () {
52     return this.replace(/\s+$/, '');
53 };
54 
55 String.prototype.caption = function () {
56     if (this) {
57         return this.charAt(0).toUpperCase() + this.substr(1);
58     }
59     return this;
60 };
61 
62 String.prototype.reverse = function () {
63     var ret = '';
64     for (var i = this.length - 1; i >= 0; i--) {
65         ret += this.charAt(i);
66     }
67     return ret;
68 };
69 
70 String.prototype.startWith = function (compareValue, ignoreCase) {
71     if (ignoreCase) {
72         return this.toLowerCase().indexOf(compareValue.toLowerCase()) == 0;
73     }
74     return this.indexOf(compareValue) == 0
75 };
76 
77 String.prototype.endWith = function (compareValue, ignoreCase) {
78     if (ignoreCase) {
79         return this.toLowerCase().lastIndexOf(compareValue.toLowerCase()) == this.length - compareValue.length;
80     }
81     return this.lastIndexOf(compareValue) == this.length - compareValue.length;
82 };