How to pass array to js in php

In web development, we often need to pass data from the back end (such as PHP) to the front end (such as JavaScript). Using AJAX technology, we can obtain back-end data asynchronously without refreshing the web page. However, in some cases, we want to directly pass the back-end array to the front-end to facilitate front-end processing. This article explains how to pass arrays to JavaScript in PHP.

1. Convert the array to JSON format

Before passing the array to JavaScript, we need to convert the array into a data structure that can be recognized in JavaScript. Here we can use JSON (JavaScript Object Notation) format, which is a text format for data exchange and a syntax for representing objects in JavaScript. PHP has a built-in json_encode() function that can convert PHP arrays into JSON format.

Sample code:

$data = array('name' => 'John', 'age' => 30, 'city' => 'New York');
$data_json = json_encode($data);
echo $data_json;

Output result:

{"name":"John","age":30,"city":"New York"}

2. Get JSON data on the front end

On the front end, we can get it through AJAX request to PHP Output JSON data, sample code:

$.ajax({
    type: "POST",  // 或者 GET
    url: "data.php",  // 后端程序地址
    dataType: "json",  // 返回的数据类型
    success: function(data) {  // 成功回调函数
        console.log(data.name);
        console.log(data.age);
        console.log(data.city);
    }
});

It should be noted that the dataType parameter specifies the data type returned by the request, here it is set to json. Therefore, if the returned JSON format is not legal, the data will not be parsed normally.

3. Directly output JSON data in PHP

In addition to converting arrays to JSON format and then outputting them in PHP, we can also directly output arrays in JSON format. This method is more concise, but requires adding the corresponding response header at the beginning of the PHP file.

Sample code:

$data = array('name' => 'John', 'age' => 30, 'city' => 'New York');
header('Content-Type: application/json');  // 响应头，指定返回的数据类型为 JSON
echo json_encode($data);

On the front end, you can directly call PHP files through AJAX without parsing.

4. Use inline scripts to pass data

In PHP files, we can also use inline scripts to pass data to JavaScript. This method is relatively simple, but difficult to maintain and is not recommended.

Sample code:

$data = array('name' => 'John', 'age' => 30, 'city' => 'New York');
echo '<script> var data = ' . json_encode($data) . '; </script>';

After the above code converts the array into JSON format, embed it directly into the script tag, and then use the variable data to access the array on the front end.

5. Use hidden input tags to pass data

If you need to submit the array in PHP when the form is submitted, we can put the array into a hidden input tag, and then When the form is submitted, it is also passed to the backend.

Sample code:

$data = array('name' => 'John', 'age' => 30, 'city' => 'New York');
echo '<form action="process.php" method="post">';
foreach ($data as $key => $value) {
    echo '<input type="hidden" name="data[&#39; . $key . &#39;]" value="&#39; . $value . &#39;">';
}
echo '<button type="submit">提交</button>';
echo '</form>';

Add an array parameter named data to the form, and then add each element in the PHP array to the hidden input tag one by one through a loop. . The entire array can be obtained via $_POST['data'] on the backend.

The above are several methods on how to pass arrays to JavaScript in PHP. Different methods can be used in different scenarios, and they need to be selected according to specific needs in actual applications.

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