Today, let's start to learn the common design patterns of JavaScript. In fact, design patterns, like algorithms, are universal and empirical ideas that deviate from the language. Front-end programmers are also software engineers, who need a solid professional foundation, and design pattern is also one of the important professional foundations of computer. what is a design pattern Design patterns are concise and elegant solutions to specific problems in the process of software design when developing business code, you are faced with a variety of different needs, and different situations will sum up different solutions. We can sum up these experiences , and make rational use of to different problems, so that we can use common solutions to solve problems . To keep it simple, design patterns can be understood as tricks and tricks when writing code. Design patterns have SOLID five design principles single function principle ( S ingle Responsibility Principle): a program only does one thing well Open and closed principle ( O pened Closed Principle): open to expansion, closed to modification Internal substitution principle ( L iskov Substitution Principle): subclasses can override the parent class and appear where the parent class appears Interface isolation principle ( I nterface Segregation Principle): keep the interface single and independent dependency inversion principle ( D ependency Inversion Principle): use methods to focus only on interfaces and not on the implementation of specific classes Front-end development uses JavaScript. We should focus on the first two principles, namely, single function principle and Open and closed principle Why do you need a design pattern Why…