JavaScript: JavaScript is a lightweight language often mentioned as a client-side scripting language that generally executes in the browsers to make interactive and dynamic web pages. It is widely used for building user-friendly creative web pages as well as non-web projects like game development, mobile apps, PDF and much more.
PHP is an Open Source language, and its source code is available free of cost to the public. Internet community owns the language and it is available for changes from its original design.
JavaScript is a non-free program and it is an open standard program maintained by the W3C and Ecma International.
PHP is characterized by a multi-threaded, blocking I/O execution model. Unlike JavaScript, PHP is synchronous. The second line of code in PHP cannot be executed until the first one is, which makes it much slower than JavaScript.
JavaScript is characterized by an event-driven, single-threaded, non-blocking I/O execution model. Such a model is ensured by the event loop and Node clustering.
PHP can be combined with HTML only. Probably the greatest advantage of PHP is the availability of CMSs like WordPress or Drupal. PHP can also be extended with any LAMP stack technology and such server solutions as MySQL or PostgreSQL
JavaScript can be combined with HTML, XML, and Ajax. There are a number of great JavaScript frameworks, and one cannot even count them because new ones emerge quite often.
PHP is a back end development language only. PHP belongs to the LAMP stack, which stands for Linux, Apache, MySQL, and HP/Perl/Python.
The greatest advantage of JavaScript over PHP lies in the fact that it is a full-stack development language. Most JS vs PHP comparisons emphasize that JavaScript is front end only, but that is simply not true. You can develop an entire web or mobile app with no other technology than JavaScript.
Stackshare.io shows that the most beloved advantages of PHP are a large community, open source, and simple deployment. PHP is used by such companies as Facebook, Lyft, Wikipedia, Slack, Tumblr, and 9 GAG.
According to stackshare.io, the main reasons why developers enjoy working with JavaScript are its universality ("Can be used on front end and back end"), popularity ("It is everywhere"), and extensibility ("there are a lot of great frameworks").
Although PHP is a general-purpose programming language, it is primarily used for developing dynamic web pages. Considering the availability of PHP-based content management systems such as Moodle and WordPress, PHP is the best solution for blogs, learning management systems, and e-commerce websites.
JavaScript has dedicated server hosting, which makes it perfectly suitable for large projects. It can be used to develop both the front end and back end of almost any software application type, including 3D games, AR/VR solutions, IoT products, and so on.