Minification, or minimization, of JavaScript source code is the process removing all characters that aren't required for proper execution. These unnecessary characters usually include formatting characters, like: whitespaces, linebreak characters, comments, and in some cases block delimeters and end-of-line characters. After minification is applied, JS code is supposed to keep its functionality.

Minification process is performed by a software or utility that analyzes and rewrites source code to reduce its size. Usually, minification process includes removal of whitespaces, shortening of variable names, and verbose functions replacement. Minification is performed on the server side and only when the source file is changed.

If done correctly, minifying JavaScript should not have any effect on the functionality of the code.But in order to make sure the minified code performs as expected, it must be thoroughly tested.If unexpected changes to the code logic and errors happen during the minification process, Issues could occur.