How to use onsubmit method to submit form data in PHP

In front-end development, there are many ways to submit form data to the back-end server. Among them, the most common method is to use the form's onsubmit method to perform the submission operation. This article will introduce how to use the onsubmit method to submit form data in PHP, and give some examples to help readers deepen their understanding.

1. Basic introduction

To use the onsubmit method in PHP, you need to add an onsubmit event to the form tag and call a JavaScript function.

onsubmit event is triggered when the form is submitted. If the form input is valid, the onsubmit event will return true, indicating that the submission is successful. Otherwise, false will be returned, indicating that the submission failed. In order to ensure the accuracy and completeness of the form data, the form data is usually verified and processed before being submitted to the backend server.

2. Implementation steps

The following are several steps to use the onsubmit method to submit form data:

1. Create an HTML form that contains the data that needs to be submitted.
2. Add an onsubmit event to the form element and specify the JavaScript function to be called.
3. The JavaScript function will be called when the form is submitted, obtain the form data, and send it to the backend server.

3. Example analysis

The following uses an example to demonstrate the use of the onsubmit method. Suppose we have the following HTML form:

<form method="post" action="submit.php" onsubmit="return validateForm()">
  <label for="name">姓名：</label>
  <input type="text" id="name" name="name">
  <br>
  <label for="email">电子邮件：</label>
  <input type="email" id="email" name="email">
  <br>
  <input type="submit" value="提交">
</form>

This form contains two input boxes, one for name and one for email. In the form's onsubmit event, we call a JavaScript function named validateForm to verify the validity of the form data. This function returns true if the form data is validated, otherwise it returns false. The following is the implementation code of this function:

function validateForm() {
  let name = document.getElementById("name").value.trim();
  let email = document.getElementById("email").value.trim();

  if (name === "" || email === "") {
    alert("请输入姓名和电子邮件");
    return false;
  } else if (!email.match(/^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/)) {
    alert("请检查电子邮件格式");
    return false;
  } else {
    return true;
  }
}

This function first obtains the name and email in the input box. Then it validates both fields. If the value in the input box is empty, then this function will pop up a dialog box prompting the user to enter their name and email. If the email format is incorrect, a dialog box will also pop up. Otherwise, this function returns true.

Note that the result returned by this function is determined before the form is submitted. If this function returns true, the form data will be submitted to the URL specified in the action attribute. Otherwise, the form data will not be submitted.

After the backend server receives the form data, it can process it accordingly. The code to submit form data can be written in the submit.php file:

<?php
  $name = $_POST["name"];
  $email = $_POST["email"];

  echo "您的姓名是 " . $name;
  echo "您的电子邮件是 " . $email;
?>

This code is very simple, it just gets the submitted name and email, and then outputs it to the screen. Of course, in actual applications, more complex operations may be performed.

4. Conclusion

This article introduces the method of using the onsubmit method to submit form data in PHP, and gives an example to illustrate the specific implementation steps. Through the introduction of this article, readers can master the basic use of the onsubmit method, so as to better implement form submission and verification.

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