Creating a Contact Form with AJAX

Build a dynamic contact form that sends user data to a server using AJAX without page reload

Understand the Problem

Problem Statement

Are you ready to add dynamic features to your contact form with AJAX and take it to the next level? We talked about the basics of making a contact form that doesn't save information locally or on a server in the last piece. We'll show you how to make a contact form that not only gets information from users but also sends it to a server so it can be processed without having to reload the page. Let's jump right in!

Problem: Create a complete contact form solution using HTML, CSS, JavaScript, and AJAX that captures user input (name, email, message) and sends it to a server-side processor without refreshing the page. The form should provide appropriate feedback to the user about the submission status.

Constraints

Form must use AJAX to send data without page reload
Must include client-side validation for required fields
Must handle form submission errors gracefully
Must provide user feedback after submission
Server-side processor must accept POST data
Form must be responsive and accessible

Examples

Example 1

Input

Form with valid data:
Name: John Doe
Email: john@example.com
Message: Hello, I'm interested in your services!

Output

Success message: "Thank you! Your message has been received."

Explanation

When user submits valid form data, AJAX sends it to server. Server processes and returns success response, which is displayed to user without page reload.

Example 2

Input

Form with invalid email format:
john.example.com

Output

Error message: "Please enter a valid email address."

Explanation

HTML5 form validation catches invalid email format and prevents submission, showing browser's native validation message.

Example 3

Input

Form submitted with server error (e.g., server down)

Output

Error message: "Error occurred. Please try again."

Explanation

When AJAX request fails due to server issues, the error callback displays a user-friendly message instead of technical error details.

Solution

/* Note: C is not typically used for web client-side development.
   This example shows a conceptual C-like pseudocode for understanding the logic */

#include <stdio.h>
#include <string.h>

// Pseudo-code representation of form validation logic
int validate_form(char *name, char *email, char *message) {
    if (strlen(name) == 0 || strlen(email) == 0 || strlen(message) == 0) {
        return 0; // Invalid
    }
    
    // Simple email validation
    if (strstr(email, "@") == NULL) {
        return 0;
    }
    
    return 1; // Valid
}

// Pseudo-code for HTTP request simulation
void send_ajax_request(char *name, char *email, char *message) {
    if (validate_form(name, email, message)) {
        printf("Sending data to server...\n");
        printf("Name: %s\n", name);
        printf("Email: %s\n", email);
        printf("Message: %s\n", message);
        printf("Success: Message sent!\n");
    } else {
        printf("Error: Invalid form data\n");
    }
}

int main() {
    // Simulate form data
    char name[] = "John Doe";
    char email[] = "john@example.com";
    char message[] = "Hello from C simulation!";
    
    send_ajax_request(name, email, message);
    return 0;
}

Time:O(1) - Constant time validation operations

Space:O(1) - Fixed amount of memory for validation

Approach:

C Pseudo-code Explanation:

Since C is not used for client-side web development, this code demonstrates the underlying logic:

validate_form(): Checks if all required fields are filled and email contains '@'
send_ajax_request(): Simulates sending data to server if validation passes
main(): Demonstrates the workflow with sample data

This illustrates the core validation and processing logic that would be implemented in JavaScript for web forms.

Visual Explanation

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All Problems