jQuery或者JavaScript實現在textarea光標處插入文本

1.Jquery函數實現：

1. $(function() {  
2.     /*  在textarea處插入文本--Start */  
3.     (function($) {  
4.         $.fn  
5.                 .extend({  
6.                     insertContent : function(myValue, t) {  
7.                         var $t = $(this)[0];  
8.                         if (document.selection) { // ie   
9.                             this.focus();  
10.                             var sel = document.selection.createRange();  
11.                             sel.text = myValue;  
12.                             this.focus();  
13.                             sel.moveStart('character', -l);  
14.                             var wee = sel.text.length;  
15.                             if (arguments.length == 2) {  
16.                                 var l = $t.value.length;  
17.                                 sel.moveEnd("character", wee + t);  
18.                                 t <= 0 ? sel.moveStart("character", wee - 2 * t  
19.                                         - myValue.length) : sel.moveStart(  
20.                                         "character", wee - t - myValue.length);  
21.                                 sel.select();  
22.                             }  
23.                         } else if ($t.selectionStart  
24.                                 || $t.selectionStart == '0') {  
25.                             var startPos = $t.selectionStart;  
26.                             var endPos = $t.selectionEnd;  
27.                             var scrollTop = $t.scrollTop;  
28.                             $t.value = $t.value.substring(0, startPos)  
29.                                     + myValue  
30.                                     + $t.value.substring(endPos,  
31.                                             $t.value.length);  
32.                             this.focus();  
33.                             $t.selectionStart = startPos + myValue.length;  
34.                             $t.selectionEnd = startPos + myValue.length;  
35.                             $t.scrollTop = scrollTop;  
36.                             if (arguments.length == 2) {  
37.                                 $t.setSelectionRange(startPos - t,  
38.                                         $t.selectionEnd + t);  
39.                                 this.focus();  
40.                             }  
41.                         } else {  
42.                             this.value += myValue;  
43.                             this.focus();  
44.                         }  
45.                     }  
46.                 })  
47.     })(jQuery);  
48.     /* 在textarea處插入文本--Ending */  
49. });  

$(文本域選擇器).insertContent("插入的內容"); 
//$(文本域選擇器).insertContent("插入的內容"，數值); //根據數值選中插入文本內容兩邊的邊界, 數值: 0是表示插入文字全部選擇，-1表示插入文字兩邊各少選中一個字符。

2.JavaScript實現：

1. function insertText(obj,str) {  
2.     if (document.selection) {  
3.         var sel = document.selection.createRange();  
4.         sel.text = str;  
5.     } else if (typeof obj.selectionStart === 'number' && typeof obj.selectionEnd === 'number') {  
6.         var startPos = obj.selectionStart,  
7.             endPos = obj.selectionEnd,  
8.             cursorPos = startPos,  
9.             tmpStr = obj.value;  
10.         obj.value = tmpStr.substring(0, startPos) + str + tmpStr.substring(endPos, tmpStr.length);  
11.         cursorPos += str.length;  
12.         obj.selectionStart = obj.selectionEnd = cursorPos;  
13.     } else {  
14.         obj.value += str;  
15.     }  
16. }  
17. function moveEnd(obj){  
18.     obj.focus();  
19.     var len = obj.value.length;  
20.     if (document.selection) {  
21.         var sel = obj.createTextRange();  
22.         sel.moveStart('character',len);  
23.         sel.collapse();  
24.         sel.select();  
25.     } else if (typeof obj.selectionStart == 'number' && typeof obj.selectionEnd == 'number') {  
26.         obj.selectionStart = obj.selectionEnd = len;  
27.     }  
28. }