European Association for Standardizing Information and Communication Systems, the association was founded in 1961 and develops standards for information systems. Members of ECMA are companies producing, selling or developing information and telecommunication systems In Europe
If you write code in ES6, you can convert it to ES5 using the Babel compiler. Babel converts all const and let into var, arrow functions into normal functions, classes into prototype inheritance, etc. The code in ES6 can be converted to ES5 using the Babel compiler. This allows you to write code in the new standard and take advantage of the facilities without worrying about compatibility.
The script can be placed practically anywhere in the HTML document, but for various reasons it is recommended to place in the section <HEAD>.
The script can also be saved in a separate file with the .js extension, in which the whole code is written without any tags <script> , </script>, because these are the elements of html.