isShowMore: function (content) {
    if(content && content.length >= 124){
        var shortContent = content.substring(0,124);
        var showMoreContent = "<pre>"+shortContent+"<div class='showMoreContent'><span>...</span><a class='btnShowMore' ms-click='showToggle(event,$index,\".questionSegment2\",question.content)'>显示全部</a></div></pre>"
        return showMoreContent;
    }else {
        return content;
    }
},
/**
 * 显示和隐藏按钮回调
 * @param e
 * @param index
 * @param _class 额外的样式
 */
showToggle: function (e, index, _class,content) {
    _class = _class || '';

    var eTxt = e.target.innerHTML
    var p = $('.textBox' + _class + '.' + index)[0]
    if (eTxt === '显示全部') {
        e.target.innerHTML = '收起'
        p.classList.add('showMore')
        $(this).prev('span').html('');

        var pre = e.target.parentElement.parentElement
        pre.firstChild.remove()
        var div = pre.querySelector('div')
        var elm = document.createElement('text')
        elm.innerText = content
        pre.appendChild(elm)
        pre.insertBefore(elm,div)

    } else {
        e.target.innerHTML = '显示全部'
        p.classList.remove('showMore')
        $(this).prev('span').html('...');

        var shortContent = content.substring(0,124);
        var pre = e.target.parentElement.parentElement
        pre.firstChild.remove()
        var div = pre.querySelector('div')
        var elm = document.createElement('text')
        elm.innerText = shortContent
        pre.appendChild(elm)
        pre.insertBefore(elm,div)
    }
},

<div class="textBox questionSegment2 no-height" ms-class="{{$index}}" ms-html="isShowMore(question.content)"></div>