js 光标选中操作

<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title></title>  
    <script src="http://libs.baidu.com/jquery/1.9.0/jquery.js"></script>  
</head>  
<body>  
<textarea name="" id="edit" cols="100" rows="10"></textarea>  
<button onclick="getPos()">获取光标位置</button>  
<button onclick="getSelect()">获取选中内容</button>  
<button onclick="insert()">插入文本</button>  
<script>  
    $.extend($.fn,{  
        //获取文本框内光标位置  
        getSelectionStart: function() {  
            var e = this[0];  
            if (e.selectionStart) {  
                return e.selectionStart;  
            } else if (document.selection) {  
                e.focus();  
                var r=document.selection.createRange();  
                var sr = r.duplicate();  
                sr.moveToElementText(e);  
                sr.setEndPoint('EndToEnd', r);  
                return sr.text.length - r.text.length;  
            }  
  
            return 0;  
        },  
        getSelectionEnd: function() {  
            var e = this[0];  
            if (e.selectionEnd) {  
                return e.selectionEnd;  
            } else if (document.selection) {  
                e.focus();  
                var r=document.selection.createRange();  
                var sr = r.duplicate();  
                sr.moveToElementText(e);  
                sr.setEndPoint('EndToEnd', r);  
                return sr.text.length;  
            }  
            return 0;  
        },  
        //自动插入默认字符串  
        insertString: function(str) {  
            $(this).each(function() {  
                var tb = $(this);  
                tb.focus();  
                if (document.selection){  
                    var r = document.selection.createRange();  
                    document.selection.empty();  
                    r.text = str;  
                    r.collapse();  
                    r.select();  
                } else {  
                    var newstart = tb.get(0).selectionStart+str.length;  
                    tb.val(tb.val().substr(0,tb.get(0).selectionStart) +  
                            str + tb.val().substring(tb.get(0).selectionEnd));  
                    tb.get(0).selectionStart = newstart;  
                    tb.get(0).selectionEnd = newstart;  
                }  
            });  
  
            return this;  
        },  
        setSelection: function(startIndex,len) {  
            $(this).each(function(){  
                if (this.setSelectionRange){  
                    this.setSelectionRange(startIndex, startIndex + len);  
                } else if (document.selection) {  
                    var range = this.createTextRange();  
                    range.collapse(true);  
                    range.moveStart('character', startIndex);  
                    range.moveEnd('character', len);  
                    range.select();  
                } else {  
                    this.selectionStart = startIndex;  
                    this.selectionEnd = startIndex + len;  
                }  
            });  
  
            return this;  
        },  
        getSelection: function() {  
            var elem = this[0];  
  
            var sel = '';  
            if (document.selection){  
                var r = document.selection.createRange();  
                document.selection.empty();  
                sel = r.text;  
            } else {  
                var start = elem.selectionStart;  
                var end = elem.selectionEnd;  
                var content = $(elem).is(':input') ? $(elem).val() : $(elem).text();  
                sel = content.substring(start, end);  
            }  
            return sel;  
        }  
    })  
</script>  
<script>  
    function getPos(){  
        alert($("#edit").getSelectionStart());  
    }  
    function getSelect(){  
        alert($("#edit").getSelection());  
    }  
    function insert(){  
       $("#edit").insertString("hello");  
  
    }  
</script>  
</body>  
</html>
js 光标选中 操作

js 光标选中操作
