项目需求，用户要能够输入和点击外面的公式去插入到textaera中，试了好几种方法，有的是在谷歌下好使，在ie下不好使，最后找到了下面这个方法，目前在ie8以上都可以生效。直接上代码  

function insertAtCursor(myField, myValue) {
        //IE support
        if (document.selection) {
            myField.focus();
            sel = document.selection.createRange();
            sel.text = myValue;
        }
        //MOZILLA and others
        else if (myField.selectionStart || myField.selectionStart == '0') {
            var startPos = myField.selectionStart;
            var endPos = myField.selectionEnd;
            myField.value = myField.value.substring(0, startPos)
                    + myValue
                    + myField.value.substring(endPos, myField.value.length);
            myField.selectionStart = startPos + myValue.length;
            myField.selectionEnd = startPos + myValue.length;
        } else {
            myField.value += myValue;
        }
    }

调用也相当的简单

insertAtCursor(‘dom节点’,‘内容’);

链接: https://fly63.com/article/detial/6127