Preprocessor in JavaScript

A preprocessor is a program or a set of codes that uses an arbitrary source file as its input data and gives output data. Another program as an input can then use this output data. Preprocessors convert files into a format that a browser or similar program is able to read or understand easily. The output delivered is a preprocessed form of input data. There are various kinds of preprocessors and the kind of processing they do depends on their characteristics/type. They can perform simple tasks such as running a macro as well as it performs highly complex tasks such as substituting a part of an entire programming language.