Alongside HTML and CSS, JavaScript is one of the three core technologies of the World Wide Web. The vast majority of websites use it, and all major web browsers have a dedicated JavaScript engine to e...Alongside HTML and CSS, JavaScript is one of the three core technologies of the World Wide Web. The vast majority of websites use it, and all major web browsers have a dedicated JavaScript engine to execute it. JavaScript is one of the most popular current programming languages [2] , and is the primary programming language for front-end web development. // This script displays "Hello world!". // // References: // https://www.w3schools.com/jsref/met_doc_write.asp document.write("Hello world!")