PHP Javascript - 数组多维错误

In practice, I create an array in PHP that then I pass to a JavaScript function.

So far so good. The array that the functions recieves is the following:

[[{"firstname": "Micheal", "lastname": "Brown"}], [{"car": "Ford", "model": "Fiesta"}]]

My problem is to get all the first array, that is this: {"firstname": "Micheal", "lastname": "Brown"}

and also the second array this: {"car": "Ford", "model": "Fiesta"}

I tried with alert (array [0]) but it only shows me this [

How can I do this?

I'll explain:

this is my php file:

class UserClasses
{
     public $firstname;
     public $lastname;
}

class CarClasses
{
     public $car;
     public $model;
}

if(isset($_POST['name'])){
     populate($_POST['name']);
}

function populate(){
//I abbreviated the function for simplicity

   $arrayUser = array();
   $arrayCar = array();

   $user = new UserClasses();
   $user->firstname = "Micheal";
   $user->lastname = "Brown";
   array_push($arrayUser, $user);

   $car = new CarClasses();
   $car->car = "Ford";
   $car->model = "Fiesta";
   array_push($arrayCar, $car);
   $arrayFinal = array($arrayUser, $arrayCar);

   print json_encode($arrayFinal);
}

and this is the function in javascript:

//Ajax for calling php function
$.post('Classes.php', { name: name }, function(data){
    var array = JSON.parse(data);
    var arrayT = array[0];
    alert(arrayT);
});

Here's what is happening with your code: you're accessing the first element of a JSON string, so my guess is you will get its first character: [.

You need to convert your string into an actual array before accessing it!

Use JSON.parse:

The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string.

- MDN web docs

For example you can do:

const json = '[[{"firstname": "Micheal", "lastname": "Brown"}], [{"car": "Ford", "model": "Fiesta"}]]'

// that's what you have
console.log(json[0])

// that's what you want
array = JSON.parse(json)
console.log(array[0])

</div>

First of all, if you are using json_encode to pass PHP array to JS, it encodes it to a JSON string. You have to parse it using JSON.parse() and only then the json string is transformed to regular array which you can use.

You can parse data and use it:

    var arr = '<?php echo '[[{"firstname": "Micheal", "lastname": "Brown"}], [{"car": "Ford", "model": "Fiesta"}]]'; ?>';
    var parsedarr =  JSON.parse(arr);

    for(var i=0;i<parsedarr.length;i++){
        console.log(parsedarr[i][0]);
    }

You are dealing with 3 different Data Types:

• a PHP Multidimensional Array
• a JSON String
• a Javascript Object

Each needs to be converted into the next.

• A PHP Array is converted into a JSON String, via json_encode() (in PHP)
• A JSON String is converted into a Javascript Object, via JSON.parse() (in Javascript)

Now you have a Javascript Object which you can interrogate and manipulate using Javascript.

PHP Multidimensional Array:

$My_PHP_Array = array(

    array(

        'firstname' => 'Michael'
        'lastname' => 'Brown'
    ),

    array(

        'car' => 'Ford'
        'model' => 'Fiesta'
    )
);

Convert PHP Multidimensional Array to JSON String:

json_encode($My_PHP_Array);

JSON String:

'{
    [
        [{
            "firstname": "Micheal",
            "lastname": "Brown"
        }],

        [{
            "car": "Ford",
            "model": "Fiesta"
        }]
    ]
}'

Convert JSON String to Javascript Object:

var myJavascriptObject = JSON.parse(myJSONString);

Javascript Object:

myJavascriptObject = {
    [
        [{
            "firstname": "Micheal",
            "lastname": "Brown"
        }],

        [{
            "car": "Ford",
            "model": "Fiesta"
        }]
    ]
};