向textarea光标停放处插入新文本-蒲公英云

向textarea光标停放处插入新文本

悠悠 2022-08-24 04:17 204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;  
    \};  
\}