How to convert table data in html to Json format

<script> 
var keysArr = new Array("key0", "key1","key2"); 
function TableToJson(tableid) { //tableid是你要转化的表的表名，是一个字符串，如"example" 
var rows = document.getElementById(tableid).rows.length; //获得行数(包括thead) 
var colums = document.getElementById(tableid).rows[0].cells.length; //获得列数 
var json = "["; 
var tdValue; 
for (var i = 1; i < rows; i++) { //每行 
json += "{"; 
for (var j = 0; j < colums; j++) { 
tdName = keysArr[j]; //Json数据的键 
json += "\""; //加上一个双引号 
json += tdName; 
json += "\""; 
json += ":"; 
tdValue = document.getElementById(tableid).rows[i].cells[j].innerHTML;//Json数据的值 
if (j === 1) {//第1列是日期格式，需要按照json要求做如下添加 
tdValue = "\/Date(" + tdValue + ")\/"; 
} 
json += "\""; 
json += tdValue; 
json += "\""; 
json += ","; 
} 
json = json.substring(0, json.length - 1); 
json += "}"; 
json += ","; 
} 
json = json.substring(0, json.length - 1); 
json += "]"; 
return json; 
} 
</script>