With the improvement of browser performance and the steady adoption of the new HTML5 programming interface, the volume of JavaScript on web pages is gradually increasing. However, a poorly written program has the potential to break the entire website, frustrate users and drive away potential customers.
Developers must use all the tools and techniques they can use to improve the quality of their code and be confident that every execution is predictable. This is a topic deep in my heart and I have worked for years to find a set of steps to follow during the development process to ensure that only the highest quality code can be published.
Just follow these seven steps to greatly improve the quality of your JavaScript project. With this workflow, errors will be reduced and many processing optimizations will be made, giving users a pleasant browsing experience.
01. Code
First, call the strict mode of ECMAScript5 and a "strict mode" declaration in your function, and use the design mode of this module. In the self-executing function closure, the use of global variables should be minimized through the sandbox independent code module, and through any external dependencies to keep the global variable module clear and concise. Only use established, proven, well-tested, well-resulted third-party library and frameworks, and keep your functions at a small value, separating any business logic or data from your module operations and other view layer code.
Larger projects with multiple developers should follow a set of established coding principles, such as Google's JavaScript style guide, and require stronger code management rules, including strict dependency management through a library such as RequireJS, using package management using asynchronous module definitions (AMD), using package management using Bower or Jam (client library management tool) to refer to specific versions of your dependency files, and adopting structural design patterns such as observer mode to facilitate loosely coupled communication between different code modules. This is also a wise idea: use a system of code repository systems, such as Git or Subversion, to get your code backed up in the cloud through some services such as source code or magic beans, provide the ability to restore to previous versions, and create a branch of code for more advanced projects to perform different functions, merge them together before completing them.
02. File
Use structured annotation block formats like YUIDoc or JsDoc to the file's functionality, so any developer can understand its purpose without studying its code, which can reduce misunderstandings. Using Markdown syntax can have richer, long comments and explanations. Use the associated command line tool to automatically generate a document on the website: based on these structural opinions, it is consistent with any modifications made in your code.
03. Track analysis
Run a static code analysis tool on your code regularly, such as JSHint or JSLint. These checks on known coding flaws and potential errors, such as forgetting to use strict patterns or referencing undeclared variables, and missing brackets or semicolons. Correct any problems with tool controls to improve the quality of your code. Try setting default options for your project team to enhance coding standards such as indenting each line by spaces, where to place curly braces, and using single or double quotes throughout the code file.
04. Test
A unit test is one of the functions performed by a small independent function: execute one of the functions from the main code base of your specific input to confirm that it outputs an expected value. To increase your confidence, the code will write frameworks used like expected, such as Jasmine or QUnit for each functional unit test, using expected and unanticipated input parameters. But don't forget those edge situations!
Run these tests on multiple browsers across multiple operating systems, allowing you to accelerate tests on virtual machines in the cloud in your demands by leveraging this service, such as BrowserStack or Sauce Labs. These two services provide an API that allows your unit tests to be automatically run on multiple browsers at the same time, and once they are completed, they will feed back the results to you. As a bonus, if your code is stored on GitHub, you can take BrowserSwarm, a tool that will automatically run your unit tests when you submit your code.
05. Measurement
Code coverage tools such as Istanbul measure which lines of code are executed when your unit test is run on your function, reporting it as a percentage of the total number of lines of code. Running a code coverage tool on your unit tests and adding additional tests can increase your coverage score to 100%, giving you greater confidence in your code.
The complexity of a function can be measured using the Hallstead complexity metric: the equation established by computer scientist Morris Hallstead in the 1970s. The complexity of a function is quantified based on loops, branches and the function calls it contains: the complexity of a function can be measured using the complexity measures of Halstead. When this complex score decreases, the easier it is to understand and maintain this function, reducing the possibility of errors. The visualization of the generated data of the command line tool Plato measures and JavaScript code complexity helps determine the functionality that can be improved while storing previous results, allowing tracking of quality improvements over time.
06. Automation
Use Task runners such as Grunt to automatically operate the process of file compilation, analysis, testing, coverage and complexity report generation, which saves you time and effort and increases your chances of solving any quality issues that arise. Most of the tools and testing frameworks highlighted in this post are associated with Grunt, which can help you improve the quality of your workflow and code without having to move a finger.
07. Handle exceptions
At the same time, at some point, your code will have an error when it runs. Use the "try… Catch" statement to properly handle runtime errors and the impact of limiting behavior on your website. Use a network service to record errors that occur while running. And use this information to add new unit tests to improve your code and eliminate these errors one by one.
Steps to Success
These seven steps help me create some of the code I am most proud of in my career so far. They are also a good foundation for the future. In your own project, we promise to use these steps to produce high-quality JavaScript code, so that we can work together to improve the network and lead to success step by step.