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Posts Tagged ‘Node.js’

complexity-report is a tool for reporting code complexity metrics in JavaScript projects. As a general rule, the more complex the code, the more buggy it is going to be. Therefore, it is a good idea to try to keep your code simple.

complexity-report is a node package which can be installed using the following command:

npm install -g complexity-report

The tool can then be run from the command line. See the complexity-report website for a list of the available options.

The tool currently reports the following metrics for each function:

Line No.
The line number on which the function’s code starts.
Physical SLOC
SLOC stands for “source lines of code”. Physical SLOC is therefore the number of physical lines of code.
Logical SLOC
The number of logical lines of code.
Parameter count
A large number of parameters can indicate that a new object should be created to group them.
Cyclomatic complexity
The number of linearly independent paths through a program’s source code. A high number is bad and generally leads to more bugs. As a rule of thumb, aim to keep the cyclomatic complexity under ten for each function.
Halstead difficulty, volume and effort
The number of bugs (B) increases with difficulty (D), volume (V) and effort (E). Estimates for the number of delivered bugs can be calculated from these metrics as B = E 2/3 / 3000 or B = V / 3000.

In addition, complexity-report also reports an overall figure for:

Maintainability
The maintainability index aims to measure the ease with which the code can be maintained in order to isolate and correct defects, meet new requirements or cope with environmental changes. It is calculated from metrics such as the number of lines of code and Halstead complexity measures.
Aggregate cyclomatic complexity
An attempt at measuring the overall cyclomatic complexity of the code.
Mean parameter count:
The mean number of parameters per function.

Phil Booth gives a good overview of the different types of complexity measured at JSComplexity.org. You also might like to take a look at Wikipedia’s entry on Halstead complexity measures for further details, including how they are calculated.

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StyleDocco is a tool for the generation of documentation and style guide documents from your CSS stylesheets. It was written by Jacob Rask and is available as a Node package under the MIT license. It includes support for SASS, SCSS, Less and Stylus.

Assuming you have first installed Node.js, you can install StyleDocco globally by simply running:
npm install -fg styledocco

The next stage is to write some stylesheet comments. Later, StyleDocco will be used to parse these comments through Markdown and display them in a generated HTML document.

Markdown converts text with four spaces at the front of each line to code blocks. StyleDocco also supports the GitHub Flavored Markdown convention of wrapping text with fenced blocks (```) to achieve the same effect. Whichever way you choose to do it, you can use this technique to write HTML code in your comments, and StyleDocco will show you a preview with the styles applied, the example HTML code underneath, and the CSS markup next to it. Whitespace before a comment block will ensure it is excluded from the documentation.

Finally, to generate the HTML style guide documents, you will need to run StyleDocco. An example command might be:
styledocco -n "My Project" -o mydocs styles
where "My Project" is the name of your project, mydocs is the name of your output directory and styles is the name of the directory containing your stylesheets.

For example, the following stylesheet:

/* Buttons
==========
Buttons for performing actions in the site.

Identifies the primary action in a set of buttons.

    <button class="btn primary">Primary</button>
*/
.btn.primary {
    background: #0000FF;
    color: #FFFFFF;
    border: 2px outset #000000;
}

/* Identifies the cancel action in a set of buttons.

    <button class="btn cancel">Cancel</button>
*/
.btn.cancel {
    background: #FF0000;
    color: #FFFFFF;
    border: 2px outset #000000;
}

/* News
==========
 Provides extra visual weight and identifies a news article.

    <div class="news">A news article</div> 
*/
div.news {
    background: #FFCC00;
	padding: 5px;
}

 

generates the following styleguide:

kalei2

Each preview includes a drag handle to help you see the effect of re-sizing it. If your project includes a README.md file, it will be used as the base for your index page.

At the bottom of the screen, there are various different options you can click to view it as it might appear on, for example, a smartphone or a laptop.

While I like StyleDocco very much, I have come across a few issues while trying it out in its current state, the first one being most serious:

  • Using IE9 or IE10, the previews are not currently visible. I haven’t yet tried it in earlier versions of IE as I don’t have VMs setup at home, but setting the browser mode to IE7 or IE8 does not resolve the issue.
  • In Chrome, the previews can be resized larger but not smaller.
  • In Firefox, resizing the browser does not resize the previews.

I would not want to introduce StyleDocco in a work environment without first looking at whether I could resolve the Internet Explorer issues.

If I were to introduce StyleDocco in a work environment, I would want to include it as part of the build process. This would enable other developers to view the documentation without necessarily having to set things up on their machine. However simple it is to set up a machine with Node.js and StyleDocco, I have found new ideas less likely to take off, the more obstacles there are to doing them. Also, once it becomes part of the build process, it effectively becomes the standard.

I look forward, next, to taking a look at another tool: Kalei Style guide by Thomas Davis.

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There are a number of node modules that can be useful tools when developing JavaScript or CSS.

In order to use one of these tools, you will first need to download and install Node.js.

Once you have installed node.js, any package can be installed by using the node package manager, npm. Any packages that the package depends upon are also automatically installed.

To install the latest version of myPackage for a single project, type the following into the command line:
npm install myPackage

Alternatively, to install the package globally, include the -g option:
npm install -g myPackage

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