Scripting and automation tasks often need to extract particular portions of text from input data or modify them from one format to another. This book will help you learn javascript Regular Expressions, a mini-programming language for all sorts of text processing needs. The book heavily leans on examples to present features of regular expressions one by one. It is recommended that you manually type each example and experiment with them. Make an effort to understand the sample input as well as the solution presented and check if the output changes (or not!) when you alter some part of the input and the code. As an analogy, consider learning to drive a car — no matter how much you read about them or listen to explanations, you'd need practical experience to become proficient. Regular Expressions is a versatile tool for text processing. You'll find them included as part of the standard library of most programming languages that are used for scripting purposes. If not, you can usually find a third-party library. Exercises are included to test your understanding. Reference solutions are also provided. You should be familiar with programming basics. You should also have a working knowledge of javascript syntax and functional programming concepts like map and filter.