为什么javascript不接受我的JSON数组?

My php file ends with:

echo json_encode($array1);
echo ";";
echo json_encode($array2);

and prints out e.g.

[1358499135965,68];[1358499140000,2]

My javascript code looks so:

function requestData() {
    $.ajax({
        url: 'livedata.php',
        success: function(point) {    
            var yenidata = point.split(";");
            alert(yenidata[0]);
            alert(yenidata[1]);
        });
    }

Why do I not get an alert?

Your JSON is not valid.

Try:

echo '[';
echo json_encode($array1);
echo ",";
echo json_encode($array2);
echo ']';

Now the PHP page will print you: [[1358499135965,68],[1358499140000,2]] Which can be parsed automatically as JSON using dataType:"json" in your ajax call.

When you include jQuery your code should look like:

function requestData() {
   $.ajax({
      url: 'livedata.php',
      dataType: 'json',
      success: function(point) {
         console.log(point[0]); //Array [1358499135965,68]
         console.log(point[1]); //Array [1358499140000,2]
      }
   });
}

Uncaught ReferenceError: $ is not defined means you're not including jQuery. You need to have that to use the features you're trying to use.