What Is JavaScript 1

What Is JavaScript

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Table of contents
1 JavaScript in WordPress
2 Organizing Scripts in a Theme
3 Standard WordPress Libraries
4 Conclusion

JavaScript is a programming language built into browsers that makes web pages “alive”. Programs in this language are called scripts. In the browser they are attached to HTML and run right after the page loads. JS lets you add dynamic elements to a site: sliders, pop-up windows, buttons, interactive forms and other interface elements.

JavaScript in WordPress

WordPress themes and plugins actively use JavaScript to create interactive and dynamic elements. The most common combination is:

  • Vanilla JS (plain JavaScript without libraries)
  • AJAX for dynamic requests without reloading the page
  • jQuery (for backward compatibility and older themes)
  • Modern frameworks in advanced themes: React, Vue.js, Alpine.js

JavaScript can be added to a theme or plugin using standard WordPress functions:

// Регистрация и подключение скрипта
wp_register_script( 'custom-js', get_template_directory_uri() . '/js/custom.js', array('jquery'), null, true );
wp_enqueue_script( 'custom-js' );

Tip: inserting JS directly into theme files (for example, header.php or footer.php) is not recommended. It is better to use wp_enqueue_script() and, if necessary, wp_localize_script() to pass data from PHP to JS.

Organizing Scripts in a Theme

Many themes contain a separate /js folder where all the JavaScript files are stored. Scripts are loaded only where they are needed. This speeds up page loading and prevents unnecessary script loading.

Example of a theme structure:

/wp-content/themes/my-theme/
├── js/
│   ├── main.js
│   ├── slider.js
│   └── popup.js
├── style.css
├── functions.php
└── index.php

Standard WordPress Libraries

WordPress includes several libraries that you can use in your themes and plugins:

  • jQuery — for backward compatibility
  • Underscore.js — utility functions
  • Backbone.js — for building structured client-side applications
  • wp.i18n — for internationalization
  • wp.apiFetch — for AJAX requests to the REST API

Example of loading a built-in library:

wp_enqueue_script( 'jquery' ); // Подключение jQuery

Conclusion

JavaScript remains the main tool for building interactive WordPress sites. Modern themes use a combination of vanilla JS, AJAX and frameworks. Well-organized and correctly enqueued JS makes a site faster, more convenient and more modern.

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