从关联数组打印JavaScript对象

Question

What if I want to console.log only one 1(ANY) javaScript object. Currenly it displays all 1000. Please Look at Php and JS files:

Server.php

if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$data = array("coordinates" => array());

$sql = "SELECT Lng, Lat, URL FROM results LIMIT 1000";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        $data["coordinates"][] = $row;
    }
}
echo json_encode($data);

Index.js

{
$.ajax({
  dataType: "json",
  url: 'server.php',
  //data: [],
  data: {param: ""},
  success: function(data)
  {
    //JSON.parse(data);  
    console.log(data);
  addMarkers(data,map);
  }
});

}

Answer 1

It helps to understand the json data structure you are outputting, and how you access certain elements from an object made by that json. In your case, you end up with a single object named data (as defined by the .ajax success callback). That object then contains just one keyname with an array of objects. The keyname is coordinates. Inside each array value, is an object from your database row return.

If you simply wish to show one object from your array of objects, this is all you need:

console.log( data.coordinates[0] );

That would show the first object in the array (arrays start with [0]).

console.log( data.coordinates[999] );

That would show the last object in the array of 1000.

console.log( data.coordinates[ data.coordinates.length-1 ] );

That would show the last object in an array of a variable size, using itself as the determiner.