如何JS在循环中修改表格标签？

Question

draw = "<div><table><tbody>";
recv = '{"张三": ["89", "63", "78", "77"], "李四": ["99", "75", "98", "97"]}';
obj = JSON.parse(recv);
for (i in obj){
    draw += "<tr><td>" + i + "</td><td>" + obj[i][0] + "</td><td>" + obj[i][1] + "</td><td>" + obj[i][2] + "</td></tr>";
}
draw += "</tbody></table></div>";
document.write(draw);

我用循环建了一个表，现在希望：
1、所有行的文字居中，也就是在draw字符串中的tr标签后添加align="center"字符串，但是直接加是报错的
2、对每次循环中的obj[i][0]进行判断，如果小于90，则在tr标签后加入“bgcolor= 字符串循环，让这一行标记颜色
请问该如何实现？

Answer 1

居中

draw = "<div><table><tbody>";
recv = '{"张三": ["89", "63", "78", "77"], "李四": ["99", "75", "98", "97"]}';
obj = JSON.parse(recv);
for (i in obj){
    draw += "<tr align='center'><td>" + i + "</td><td>" + obj[i][0] + "</td><td>" + obj[i][1] + "</td><td>" + obj[i][2] + "</td></tr>";
}
draw += "</tbody></table></div>";
document.write(draw);

判断并且改变颜色

draw = "<div><table><tbody>";
recv = '{"张三": ["89", "63", "78", "77"], "李四": ["99", "75", "98", "97"]}';
obj = JSON.parse(recv);
for (i in obj){
    if (obj[i][0] < 90){
        draw += "<tr align='center' bgcolor='red'><td>" + i + "</td><td>" + obj[i][0] + "</td><td>" + obj[i][1] + "</td><td>" + obj[i][2] + "</td></tr>";
    }else{
        draw += "<tr align='center'><td>" + i + "</td><td>" + obj[i][0] + "</td><td>" + obj[i][1] + "</td><td>" + obj[i][2] + "</td></tr>";
    }
}
draw += "</tbody></table></div>";
document.write(draw);