What is the difference between client-side and server-side programming?

web-development

client-server

ajax

server-side-validation

byNikita Barsukov·Sep 16, 2024

The principal distinction between client-side and server-side drills down to their execution location:

Client-side involves scripting languages such as JavaScript running in the user's web browser, dealing predominantly with dynamic web interfaces and end-user experiences.

// Sherlock Holmes level input validation. Client-side stuff.
document.getElementById('submit').onclick = () => {
  if (!document.getElementById('name').value) {
    alert('Dear user, even Voldemort has a name!');
    return false;
  }
};

Server-side, on the other hand, involves backend languages like Node.js handling data processing and business logic.

// Here we handle submission. The magic happens in the server
app.post('/submit', (req, res) => {
  if (!req.body.name) {
    res.status(400).send('Name is as essential as coffee for developers!');
    return;
  }
  // Here is where we play with databases. Shh... Let them sleep for now.
});

In simpler terms, client-side is the visible part users see and interact with, while server-side is the invisible hero running the show behind the curtain.

Delving deeper: Execution and interaction on both sides

Execution ground: Client vs Server

Client-side code gets executed in the user's browser, mainly determining user interaction, UI updates, and dynamic content changes without page reload. Server-side code, contrastingly, runs on the server-side, handling tasks such as database interactions, file management, and authentication.

User state tracking: The role of server-side

As the HTTP protocol is stateless, server-side programs are essential to establish a link between incoming requests and correct user data, hence tracking user state and sessions.

// Snoop into session data, orders from the client-side
$.ajax({
  url: '/getSessionData',
  success: function (data) {
    console.log('Received session data: ', data);
  }
});

// Server-side mission - manage session data like a boss
session_start();
$_SESSION['user_data'] = $user_data;

Client-server communication: Feat AJAX

For an enriched user experience that makes applications feel more like native software, client-side uses asynchronous mechanisms such as AJAX or Fetch API for interaction with the server without page reload.

// Client-side, using Fetch API to send data, no refresh needed.
fetch('/submit-form', {
  method: 'POST',
  body: JSON.stringify(formData),
  headers: { 'Content-Type': 'application/json' }
})
.then(response => response.json())
.then(data => console.log('Data from server: ', data))
.catch(error => console.error("Houston, we have a problem! Error: ", error));

Sensitive operations and file handling: The realm of server-side

Operation confidentiality

Operations which bear crucial significance such as security or file operations should be exclusively server-side to prevent unsolicited access. Finer control over access rights, file creation, or database connections is a perk of the server environment.

<?php
// Server-side gets to write to secure files. That's power!
$file = fopen('secure-data.txt', 'w');
fwrite($file, 'Super secret data');
fclose($file);
?>

Concern separation for security

While it's viable to validate users' inputs on the client-side using JavaScript, echo this validation on the server to prevent end-user manipulation as client-side code can be altered whereas server-side code stands invulnerable.

// Server-side validation, because not all that glitters is gold
if (empty($_POST["name"])) {
  // Name is found wanting
  die("Name required. Instructions unclear, got lost in code.");
}

Power of performance and smooth maintainability

Fast load times, courtesy of client-side

By rendering client-side, a hefty load can be offloaded from the server, which reduces server load and may accelerate page load times as minimal data is dispatched over the network.

Code segregation is key

Maintaining a lucid separation between client and server-side logic paves the way for simplified maintainability. Frameworks and libraries come in handy to construct applications in a way that supports scalability.

explain-codes / Web development / What is the difference between client-side and server-side programming?

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