d3.json没有从我的php api返回数据值

Question

I'm trying to load data from my php api onto d3.json so that I can visualise it as a line chart.

This is my code:

d3.json("api.php", function(error, data) {
    var k = [];
      data.forEach(function(d) {
          d.date = d.date;
          d.close = +d.close;
          k.push(d.date)
      })
});

when I run console.log(k) to see if it did load data. It prints nothing.

This is a sample of my api.php:

[  
   {  
      "id":"1",
      "exchange_symbol":"TSE",
      "currency":"JPY",
      "stock_id":"1",
      "stock_name":"KYOKUYO CO.,LTD.",
      "stock_symbol":"1301.T",
      "date":"2006-12-29",
      "time":"15:00:00.000000",
      "close":"2388.023438000000000000",
      "volume":"23700.000000000000000000",
      "active":"1",
      "exchange_id":"0"
   }   ...
]

What have I done wrong? Thanks in advance guys.