PHP study notes: human-computer interaction and user experience

PHP study notes: Human-computer interaction and user experience, specific code examples are needed

Introduction:
In modern Web application development, human-computer interaction and User experience is crucial. A user-friendly and well-interactive website can attract more visitors and improve user satisfaction, thereby indirectly increasing the website's conversion rate and profitability. In the development process of PHP, we can use some technologies and methods to improve human-computer interaction and user experience, and in this article, some specific code examples will be given.

1. Dynamic form validation
When users enter data, we can use AJAX and PHP to perform dynamic form validation to improve user feedback speed and user experience. The following is a sample code for dynamic form validation via AJAX and PHP:

HTML code:

<form method="post" action="process.php">
    <input type="text" name="username" id="username" onblur="checkUsername()">
    <span id="username-error"></span>
    <input type="password" name="password">
    <input type="submit" value="提交">
</form>

JavaScript code:

function checkUsername() {
    var username = document.getElementById("username").value;
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4 && xhr.status == 200) {
            document.getElementById("username-error").innerHTML = xhr.responseText;
        }
    };
    xhr.open("GET", "check_username.php?username=" + encodeURIComponent(username), true);
    xhr.send();
}

PHP code (check_username.php):

<?php
$username = $_GET["username"];
// 在这里进行用户名的验证逻辑
if (用户名已存在) {
    echo "用户名已存在";
} else {
    echo "";
}
?>

Through the above code, when the user completes inputting in the username input box and loses focus, the checkUsername() function will be automatically triggered. This function uses AJAX and check_username.php Communicate, return the verification results and display them on the page so that users can get immediate feedback.

2. Friendly error handling
In Web applications, error handling is a very important part, and reasonable error message display is very helpful to users. The following is a sample code for handling database connection errors:

PHP code:

<?php
$conn = mysqli_connect("localhost", "username", "password", "database");
if (!$conn) {
    die("数据库连接失败：" . mysqli_connect_error());
}
?>

In the above code, if the database connection fails, a friendly error message will be displayed. In this way, users can understand the specific cause of the error, and developers can debug and fix it more conveniently.

3. AJAX non-refresh paging
The traditional paging method requires the user to click the page number or the previous page and next page buttons, and then refresh the entire page to obtain new content, which brings inconvenience to the user. Using AJAX refresh-free paging technology, you can load new data without leaving the current page. The following is a simple AJAX non-refresh paging example code:

HTML code:

<div id="content"></div>
<button onclick="loadMore()">更多</button>

JavaScript code:

var page = 1;

function loadMore() {
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4 && xhr.status == 200) {
            document.getElementById("content").innerHTML += xhr.responseText;
        }
    };
    xhr.open("GET", "load_more.php?page=" + page, true);
    xhr.send();
    page++;
}

PHP code (load_more.php):

<?php
$page = $_GET["page"];
$limit = 10;
$start = ($page - 1) * $limit;
// 获取数据库中的数据
$rows = mysqli_query($conn, "SELECT * FROM table LIMIT $start, $limit");

while ($row = mysqli_fetch_array($rows)) {
    // 显示数据
}
?>

Through the above code, when the user clicks the "More" button, new data will be loaded through AJAX and displayed on the current page. The user does not need to leave the current page to obtain new content.

Conclusion:
For PHP developers, it is very beneficial to understand and master the technologies and methods of human-computer interaction and user experience. In this article, specific code examples in three aspects: dynamic form validation, friendly error handling, and AJAX refresh-free paging are introduced. Through these examples, we hope to help developers improve human-computer interaction and user experience, thereby making web applications more friendly and efficient.

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