js实现类似qq表情（插入图片以及获取光标的效果）

<!doctype html>
<html style="height:100%">
<head>
<meta charset="utf-8">
<title>无标题文档</title>
</head>

<body>
<div class="popover-content">
   <ul class="list-inline emote_list">
      <li data-key="1f60a" class="emote_item"><img alt="" src="/static/img/emoteicon/1f60a.png"></li>
      <li data-key="1f60d" class="emote_item"><img alt="" src="/static/img/emoteicon/1f60d.png"></li>
      <li data-key="1f618" class="emote_item"><img alt="" src="/static/img/emoteicon/1f618.png"></li>
      <li data-key="1f633" class="emote_item"><img alt="" src="/static/img/emoteicon/1f633.png"></li>
   </ul>
</div>
<textarea placeholder="" class="form-control" id="input_textarea" style="100%; height:100px; border:1px solid red"></textarea>
<button class="btn btn-primary" type="button" id="btn_send">发送</button>
</body>
</html>
<script src="jquery.min.js"></script>
<script type="text/javascript">

// 获取光标位置函数
function getCursortPosition(ctrl) {
    var CaretPos = 0;
    if (document.selection) { // IE Support
        ctrl.focus();
        var Sel = document.selection.createRange();
        Sel.moveStart('character', -ctrl.value.length);
        CaretPos = Sel.text.length;
    } else if (ctrl.selectionStart || ctrl.selectionStart == '0') { // Firefox support
        CaretPos = ctrl.selectionStart;
    }
    return (CaretPos);
}

$(document).ready(function() {
    $('.emote_item').on('click', function() {
        var k = $(this).data('key'),
        input = $('#input_textarea');
        pos = getCursortPosition(input[0]);
        s = input.val();
        var v = s.substring(0, pos) + '[e]' + k + '[/e]' + s.substring(pos);
        input.val(v);
        input.focus();

    });
});
</script>

//第二种插入光标处的插件

//插入光标处的插件
    $.fn.extend({
        insertContent : function(myValue, t) {

            var $t = $(this)[0];
            if (document.selection) {
                this.focus();
                var sel = document.selection.createRange();
                sel.text = myValue;
                this.focus();
                sel.moveStart('character', -l);
                var wee = sel.text.length;
                if (arguments.length == 2) {
                var l = $t.value.length;
                sel.moveEnd("character", wee + t);
                t <= 0 ? sel.moveStart("character", wee - 2 * t - myValue.length) : sel.moveStart("character", wee - t - myValue.length);
                sel.select();
                }
            } else if ($t.selectionStart || $t.selectionStart == '0') {
                var startPos = $t.selectionStart;
                var endPos = $t.selectionEnd;
                var scrollTop = $t.scrollTop;
                $t.value = $t.value.substring(0, startPos) + myValue + $t.value.substring(endPos,$t.value.length);
                this.focus();
                $t.selectionStart = startPos + myValue.length;
                $t.selectionEnd = startPos + myValue.length;
                $t.scrollTop = scrollTop;
                if (arguments.length == 2) {
                    $t.setSelectionRange(startPos - t,$t.selectionEnd + t);
                    this.focus();
                }
            } else {
                this.value += myValue;
                this.focus();
            }
            var val = $(this).val(),
                that = $(this),
                box = that.parent().prev('.dynamic_info').find('.right');

                if(val.length > 140){
                    that.val(val.substring(0, 140));
                    box.html('您还可以输入0字');
                    return false;
                }else{
                    box.html('您还可以输入' + (140 - val.length) + '字');
                }
        }
    })
     //插入光标处的插件end

//使用方法：

//当前文本框
var obj = that.parents('.face_content_item').prev('.face_textarea_item').find('.contents');
//点击表情插入文本框
$('.jsSmilies li').click(function() {
var _text = $(this).data('action');
obj.focus();
obj.insertContent(_text);
$(this).parents('#xuebox_smilies').hide();
})