Html title屬性值不能正確應用於td元素動態地？

在這裏，我使用JSON數據動態生成表。表生成是好的，現在我想顯示標題屬性中的值在特定的領域。Html title屬性值不能正確應用於td元素動態地？

例如。我需要表現出對客戶端代碼的title屬性「客戶端」值

MY jQuery代碼

var data = [ 
    { 
     "Client Code": "ADV", 
     "Project Code": "-001", 
     "Work Description": "test record 1", 
     "Location": "O", 
     "Date": "28-09-2016", 
     "Duration": "1.50", 
     "Recordid": "43887", 
     "Client": "Adivtek Parcel Services", 
     "Projects": "Hello", 
     "Delete": "Delete", 
     "StatusFlag": "0", 
     "RowNumber": "1" 
    } 
]; 

var cont = parent.find("tbody"); 
var html = "<tr>"; 
var td = ""; 
var title_string = ""; 
for (var i = 0; i < cols.length; i++) 
{ 
    if (cols[i] == "Client Code") 
    { 
     title_string = data.Client; 
    } 
    else if (cols[i] == "Project Code") 
    { 
     title_string = data.Projects; 
    } 
    else 
     title_string = ""; 
    td = "<td title=" + title_string + ">"; 

    html += td + data[cols[i]] + "</td>"; 
} 
html += "</tr>"; 
cont.append(html);

現在我的輸出是