input 和 textarea 输入框最大文字限制插件

/* input 和 textarea 最大文字限定插件
02  * 修改版, 一个中文表示1一个字, 一个英文半个字;
03  * TextLimit - jQuery plugin for counting and limiting characters for input and textarea fields
04  * 
05  * pass '-1' as speed if you don't want the char-deletion effect. (don't just put 0)
06  * Example: jQuery("Textarea").textlimit('span.counter',256)
07  *
08  * $Version: 2009.07.25 +r2
09  * Copyright (c) 2009 Yair Even-Or
10  * vsync.design@gmail.com
11 */
12 ; 
13 String.prototype.getBytes = function () {
14     var cArr = this.match(/[^\x00-\xff]/ig);
15     return this.length + (cArr == null ? 0 : cArr.length);
16 };
17 (function(jQuery) {
18     jQuery.fn.textlimit=function(counter_el, thelimit, speed) {
19         var charDelSpeed = speed || 15;
20         var toggleCharDel = speed != -1;
21         var toggleTrim = true;
22         var that = this[0];
23         var isCtrl = false; 
24         updateCounter();
25           
26         function updateCounter(){
27             if(typeof that == "object")
28                 jQuery(counter_el).text(thelimit - Math.ceil(that.value.getBytes()/2));
29         };
30           
31         this.keydown (function(e){ 
32             if(e.which == 17) isCtrl = true;
33             var ctrl_a = (e.which == 65 && isCtrl == true) ? true : false; // detect and allow CTRL + A selects all.
34             var ctrl_v = (e.which == 86 && isCtrl == true) ? true : false; // detect and allow CTRL + V paste.
35             // 8 is 'backspace' and 46 is 'delete'
36             if( this.value.length >= thelimit && e.which != '8' && e.which != '46' && ctrl_a == false && ctrl_v == false)
37                 e.preventDefault();
38         })
39         .keyup (function(e){
40             updateCounter();
41             if(e.which == 17)
42                 isCtrl=false;
43   
44             if( this.value.length >= thelimit && toggleTrim ){
45                 if(toggleCharDel){
46                     // first, trim the text a bit so the char trimming won't take forever
47                     // Also check if there are more than 10 extra chars, then trim. just in case.
48                     if ( (this.value.length - thelimit) > 10 )
49                         that.value = that.value.substr(0,thelimit+100);
50                     var init = setInterval
51                         ( 
52                             function(){ 
53                                 if( that.value.length <= thelimit ){
54                                     init = clearInterval(init); updateCounter() 
55                                 }
56                                 else{
57                                     // deleting extra chars (one by one)
58                                     that.value = that.value.substring(0,that.value.length-1); jQuery(counter_el).text(Math.ceil(that.value.getBytes()/2));
59                                 }
60                             } ,charDelSpeed 
61                         );
62                 }
63                 else this.value = that.value.substr(0,thelimit);
64             }
65         });
66           
67     };
68 })(jQuery);
posted @ 2011-11-09 09:42  peterlee  阅读(271)  评论(0)    收藏  举报