JavaScript Minification | Benefits and Working Process

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May 4, 2024

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JavaScript Minification is a process of optimizing the JavaScript code by removing unwanted characters, data, and blank spaces without affecting its functionality. This process reduces the file size of the code, enabling faster download of the file, which in turn improves the performance of the Web application. Therefore, the minification process is highly beneficial to Websites that have multiple user interactive functionalities incorporated through JavaScript codes.

1. How Does Minification Work?

There are many tools available on the Web that help minify JavaScript code. These tools will take the code as the input and provide the minified code as the output. Tominify, the tools analyze the inputted script, remove any redundant text, such as comments, blank spaces, and lengthy variables, and thereby, reduce the file size. This modification process is done on the server side before the response is sent to the browser. CSS and other components that are utilized by Web browsers to render a Website can also be minified.

2. Step-By-Step Minification Process

There are multiple techniques available to minify the code, such as shortening the variable names, removing the whitespaces, and making the functions crisper. Essentially, all techniques of minification ensure that the functionality of the script is kept intact, which in turn ensures that the Web browser will function as required. However, a minified script is harder to read than a normal script. The minification process happens on the Web server side deploys the file and responds to a request from the end user.

The steps of the minification process are as follows:

• The user makes a request: A user requests a Web browser for a Web page.
  
  
• Minification process: The web server lets the page be processed by an online Minification tool.
  
  
• The minified script is called on: The web server deploys the minified file and responds to the browser.
  
  
• Swifter functioning: The Web page functions as expected with a lesser bandwidth used.
  
  

3. Advantages of JavaScript Minification:

Minification offers benefits such as:

• The download time of a Web page is decreased as the file size is reduced by removing unwanted text from the code.
  
  
• The script execution time is reduced.
  
  
• The bandwidth consumption of the Web site is reduced.
  
  
• The number of HTTP requests to the Web server is reduced, which reduces the server load and enables more users to access the Website simultaneously.
  
  

As Websites now need to download smaller files, they load faster and use less bandwidth. Therefore, the performance of Websites is enhanced due to minification. The benefit accrued by reduced bandwidth usage could be minimal for Websites that have only a few users. However, the reduction in bandwidth usage due to minification makes a significant difference for large e-commerce platforms and social Websites, such as Facebook and Twitter.

JavaScript Minification Tools

Many online tools are available for minifying JavaScript code. The primary goal of JavaScript minification is to retain the functional quality of the code while reducing the file size. As part of the HTTP protocol, usually, all JavaScript and CSS files transferred by Web servers are zipped.

• YUI Compressor: The YUI Compressor is a command-line tool developed by Yahoo. It is written in Java and can be used to minify both JavaScript and CSS. The compression ratio is much better than any other JavaScript minification tool. YUI Compressor delivers over 20% of HTTP compression, which is 10 percent better than what other minification tools offer.
  
  
• JSCompress: JSCompress is an online compression tool that is used to minify files up to 80% of their original size. Several JavaScript files can be merged and compressed by uploading them to the JSCompress site.
  
  
• JSMin: The JSMin JavaScript minifying tool is used to remove redundant comments and whitespaces from JavaScript files. The file size of a JavaScript file can be reduced to half its original size, which helps in downloading a Web page faster.
  
  
• Packer: Packer is a familiar JavaScript minifying tool. It creates a minified version of the code. The Web developer can paste the original code in the minified toolbox and click the 'Pack' button to get the minified output. This output can be used on the Web page.
  
  
• Dojo ShrinkSafe: The Dojo ShrinkSafe uses the Rhino library to resolve the JavaScript code. It does not modify a public variable or an API used in the script. So, the compressed version of the JavaScript code can be used as such on the Web page.
  
  
• Ajaxmin Ui: AjaxminUi minifies all the JavaScript files in a folder and nested folders. The minifying operation is charged in the background. The tool also analyzes the code productivity and shows the results in a productive directory at the end of the minifying operation.
  
  
• JavaScript Optimizer (JSO): Apart from minifying the code, the JSO can administer JavaScript and CSS sources. It can even reduce the exchange of data between the server and the client cache. It helps in optimizing the cache and to combine JavaScript files.
  
  
• DigitalOverload Tool: The most commonly used minification tool is the JavaScript minifier, DigitalOverload. The results are exclusive, tactical, and well-prepared.
  
  
• Gulp Tool: Gulp is an easy-to-use command-line minification tool that uses the Uglify JS compressor. The compressor provides an API called Tree Walker that parses through every node of the JavaScript code. Thus, the tool efficiently performs complicated tasks.
  
  

Minifying Using Google Closure Compiler

Google Closure Compiler is a robust JavaScript minification tool. It reduces the JavaScript code by assessing it, eliminating the dull code, modifying badly written codes, and removing the leftovers. It verifies the syntax, provides suggestions, and notifies the drawbacks of the code.

Steps to Process a File with the Closure Compiler:

• Step 1: Save the JavaScript code in a file.
  
• Step 2: Upload the file to a Web server.
• Step 3: Compose a POST request to the Closure Compiler service after substituting the js_code parameter with a code_url parameter.
  
• Step 4: The URL of the file can be obtained from the web server. The same must be the value of code_URL.
  
  

Benefits of Closure Compiler:

Using the Closure Compiler for minification provides several benefits, such as:

• Productivity: Reduced file size and faster loading of a Web page.
• Competent: Enhanced performance of a Web page.
• Code Inspection: Added feature of giving warnings for the use of notations from other programming languages and potential error-prone operations.
• Maintenance: Increased assistance in producing JavaScript code that has fewer errors and is easy to maintain.
  
  

Closure Compiler Service Ul:

The Closure Compiler API can be accessed from http://closure-compiler.appspot.com.

Communicating with the Closure Compiler Service API:

The Closure Compiler service API helps to employ the compiler service via an HTML form in a Web page. Closure Compiler service can be communicated using the HTTP POST method in the form. With each request, at the very least, the following parameters need to be sent:

Parameter:

• js_code or code_url
• compilation_level
• output_info
• compiled_code
• output_format
  
  

What does it do:

• The value of this parameter informs JavaScript what needs to be compiled. At least one of these parameters, if not both, must be included in the request.
• Three possible compilation levels can be applied to the JavaScript code that defines the degree of compression and optimization required.
• The value of this parameter signifies the kind of information being called from the compiler.
• It instructs the Closure Compiler service to provide a compressed version of the JavaScript code.
• Informs the compiler about the output file format.
  
  

Additional Information:

1. (

• The js_code parameter needs to be a string; for example, alert('hello').
• The code_url parameter needs to carry the URL of a JavaScript .js file, which would be available via HTTP.
  )
  

2. (

• SIMPLE_OPTIMIZATIONS
• WHITESPACE ONLY
• ADVANCED OPTIMIZATIONS
  )

3. ( Outputs can be of four kinds:

• compiled_code
• warnings
• errors
• statistics
  )

4. ( ... )

5. (

• Output formats can be of three kinds i.e. text, XML, or JSON, The default value of the output_format parameter is text.
  )
  
  

Improve the Compression

When the compilation_level is WHITESPACE ONLY, whitespaces and comments are only removed. SIMPLE_OPTIMIZATIONS compression level can achieve better compression than WHITESPACE ONLY.

What is the Amount of Compression Achieved?

To find the data saved, change output_info in request parameters from compiled_code to compiler_statistics. Compressed JavaScript is less than half in size as compared to the original code, as is obvious from the statistics obtained.
Compilation: 0
Actual: 1372
Compressed: 677