Summary of php related issues

This article mainly shares with you a summary of PHP-related issues, mainly the problems we usually encounter. I hope it can help everyone.

1. Talk about your understanding of JavaScript closures?

Simply put, it is the application of scope: local variables and global variables.

Variables defined inside the function cannot be accessed outside the function, so the function is said to constitute a closure.

2. How to solve the AJAX cross-domain calling problem?

Two methods: 1. Server side:

Use the Access-Control-Allow-Origin header on the request page

                    header("Access-Control-Allow-Origin: http://www.abc.com"); //允许指定网站
                    header("Access-Control-Allow-Origin: *");//允许所有网站
                    2.jsonp

ajax.js file:

  <script type="text/javascript">
    $.ajax({
        dataType: "jsonp",
        url: "http://www.b.com/b.php",
        jsonp: "callback",
        success: function(data) {
            $(".info").text("uid:" + data.uid + " name:" + data.name);
        }      
    });
    </script>
ajax.php文件：
<?php 
$callback = !empty($_GET[&#39;callback&#39;]) ? trim($_GET[&#39;callback&#39;]) : &#39;&#39;; 
if(!empty($callback)) {
    $data = json_encode(array(
        &#39;uid&#39; => 1,
        &#39;name&#39; => &#39;测试&#39;,
    ));   
    echo "{$callback}({$data});";
}

3. What is the difference between AJAX asynchronous and synchronous?

Asynchronous: When this AJAX code is running, other codes can also run. Synchronization: Wait for this ajax code to finish running before executing other functions. Set by async:false parameter, default true (asynchronous).

4. Talk about your understanding of MVC?

M(Model): Business rules for data V(View): The interface that users see and interact with C(Controller): Receive user data and call models and views to complete user needs.

Summary:

The model sends the functions to be implemented to the controller, and the controller receives the organizational functions and passes them to the view;

5. How to understand Single entrance and multiple entrances?

Single entrance: All requests of the web program are directed to a script file. Multiple entries: Complete user requests by accessing different files.

Related recommendations:

Concurrency - PHP questions for newbies

PHP question collection

php problem

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