var empList = ' <li data-view-section="details">'+
      '<span>Hello world</span>'+
     '</li>';

var empList = ' <li data-view-section="details">\
      <span>Hello world</span>\
    </li>';

function StringBuffer(){
  this.buffer = [];
}
//将新添加的字符串添加到数组中
StringBuffer.prototype.append = function(str){
  this.buffer.push(str);
  return this;
};
//转成字符串
StringBuffer.prototype.toString = function(){
  return this.buffer.join("");
};
//用法
var buffer = new StringBuffer();
buffer.append("hello");
buffer.append(',world');
console.log(buffer.toString());