向textarea光标停放处插入新文本

悠悠 2022-08-24 04:17 134阅读 0赞

//==================================================================================================Control类  
var Control = \{  
    /\*\*  
     \* @param \{HTMLElement\} textarea  
     \*/  
    TextArea:function(textarea)\{  
        var o = textarea;  
        var start = 0;  
        var end = 0;  
          
        var savepos = function()\{  
            //如果是Firefox(1.5)的话，方法很简单  
            if(typeof(o.selectionStart) == "number")\{  
                start = o.selectionStart;  
                end = o.selectionEnd;  
            \}  
            //下面是IE(6.0)的方法，麻烦得很，还要计算上'/n'  
            else if(document.selection)\{  
                var range = document.selection.createRange();  
                if(range.parentElement().id == o.id)\{  
                    // create a selection of the whole textarea  
                    var range\_all = document.body.createTextRange();  
                    range\_all.moveToElementText(o);  
                    //两个range，一个是已经选择的text(range)，一个是整个textarea(range\_all)  
                    //range\_all.compareEndPoints()比较两个端点，如果range\_all比range更往左(further to the left)，则  
                    //返回小于0的值，则range\_all往右移一点，直到两个range的start相同。  
                    // calculate selection start point by moving beginning of range\_all to beginning of range  
                    for(start=0; range\_all.compareEndPoints("StartToStart", range) < 0; start++) range\_all.moveStart('character', 1);  
                    // get number of line breaks from textarea start to selection start and add them to start  
                    // 计算一下/n  
                    for(var i = 0; i <= start; i ++)\{  
                        if (o.value.charAt(i) == '/n') start++;  
                    \}  
                    // create a selection of the whole textarea  
                    var range\_all = document.body.createTextRange();  
                    range\_all.moveToElementText(o);  
                    // calculate selection end point by moving beginning of range\_all to end of range  
                    for(end = 0; range\_all.compareEndPoints('StartToEnd', range) < 0; end ++) range\_all.moveStart('character', 1);  
                    // get number of line breaks from textarea start to selection end and add them to end  
                    for (var i = 0; i <= end; i ++)\{  
                        if (o.value.charAt(i) == '/n') end ++;  
                    \}  
                \}  
            \}  
        \};  
          
        lee.addEvent(o, 'keydown', savepos);  
        lee.addEvent(o, 'keyup', savepos);  
        lee.addEvent(o, 'mousedown', savepos);  
        lee.addEvent(o, 'mouseup', savepos);  
        lee.addEvent(o, 'focus', savepos);  
          
        this.insert = function(text)\{  
            var pre = o.value.substr(0, start);  
            var post = o.value.substr(end);  
            o.value = pre + text + post;  
        \};  
    \}      
\};