关于html selection 的经典示例

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>光标控制器</title>
    <script type="text/javascript">
        function CursorControl(a){
            this.element=a;
            this.range=!1;
            this.start=0;
            this.init();
        }
        CursorControl.prototype={
            init:function(){
                var _that=this;
                this.element.onkeyup=this.element.onmouseup=function(){
                    this.focus();
                    if(document.all){
                        _that.range=document.selection.createRange();
                    }else{
                        _that.start=_that.getStart();
                    }
                }
            },
            getType:function(){
                return Object.prototype.toString.call(this.element).match(/^\[object\s(.*)\]$/)[1];
            },
            getStart:function(){
                if (this.element.selectionStart || this.element.selectionStart == '0'){
                    console.log(this.element)
                    console.log(window.getSelection())
                    console.log(window.getSelection().getRangeAt(0))
                    return this.element.selectionStart;
                }else if (window.getSelection){
                    console.log(window.getSelection());
                    console.log(window.getSelection().getRangeAt(0))
                    var r = document.createRange();
                    console.log(r)
                    var rng = window.getSelection().getRangeAt(0).cloneRange();
                    rng.setStart(this.element,0);
                    return rng.toString().length;
                }
            },
            insertText:function(text){
                this.element.focus();
                if(document.all){
                    document.selection.empty();
                    this.range.text = text;
                    this.range.collapse();
                    this.range.select();
                }
                else{
                    if(this.getType()=='HTMLDivElement'){
                        this.element.innerHTML=this.element.innerHTML.substr(0,this.start)+text+this.element.innerHTML.substr(this.start);
                    }else{
                        this.element.value=this.element.value.substr(0,this.start)+text+this.element.value.substr(this.start);
                    }
                }
            },
            getText:function(){
                if (document.all){
                    var r = document.selection.createRange();
                    document.selection.empty();
                    return r.text;
                }
                else{
                    if (this.element.selectionStart || this.element.selectionStart == '0'){
                        var text=this.getType()=='HTMLDivElement'?this.element.innerHTML:this.element.value;
                        return text.substring(this.element.selectionStart,this.element.selectionEnd);
                    }
                    else if (window.getSelection){
                        return window.getSelection().toString()
                    }
                }
            }
        };
        var c1,c2;
        window.onload=function(){
            c1 = new CursorControl(document.getElementById('text'));
            c2 = new CursorControl(document.getElementById('editdiv'));
        };
        function fn1(str){
            c1.insertText(str);
        }
        function fn2(str){
            c2.insertText(str);
        }
        function fn3(){
            alert(c1.getText());
        }
        function fn4(){
            alert(c2.getText());
        }
    </script>
</head>
<body>
<input type="button" value="插入字符串 {文本1}" onclick="fn1('{文本1}');"/>
<input type="button" value="获取选中的文本" onclick="fn3();"/><br/><br/>
<div>
<textarea >这里是文本框</textarea><br/><br/>
</div>
<input type="button" value="插入字符串 {文本2}" onclick="fn2('{文本2}');"/>
<input type="button" value="获取选中的文本" onclick="fn4();"/><br/><br/>
<div >这里是一个可编辑层</div><br/>
</body>
</html>