Adding JSLint To Your Build

On December 2, 2011, in Uncategorized, by derekgreer

JSLint, the popular JavaScript static code analysis tool written by Douglas Crockford, can fairly easily be incorporated into your builds through the use of node and the jslint node module.  The following steps will show you how to add JSLint to an existing rake build:

Step 1: Install Node

If you don’t already have it, go download and install node from http://nodejs.org/.

Step 2: Add JSLint Method

The following jslint method uses the Node Package Manager (npm) to install the jslint module into the current folder if it does not already exist.  If node or npm are not found in the execution path then an error message is printed and the method simply returns.  The method uses a hash config parameter for its parameters.

def jslint(config)
    tool = 'jslint'
    flags = config['flags'] || ''

    node = which('node')
    if(node.nil?)
        puts "Could not find node in your path."
        return
    end

    npm = which('npm')
    if(npm.nil?)
        puts "Could not find npm in your path."
        return
    end

    if(!File.directory?("node_modules/#{tool}"))
        sh "\"#{npm}\" install #{tool}"
    end

    scripts = config['scripts'] || [""]
    sh "\"#{node}\" node_modules/#{tool}/bin/#{tool}.js #{flags} #{scripts}"
end

def which(cmd)
    exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
    ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
    exts.each { |ext|
        sep = File::ALT_SEPARATOR || File::SEPARATOR
        exe = "#{path}#{sep}#{cmd}#{ext}"
        return exe if File.executable? exe
    }
    end
    return nil
end

Step 3: Add a Lint Task

After including the jslint method defined above, add a new rake task which calls the method with the desired config values:

    task :lint do
        config = { 'flags'   => '--white',
                   'scripts' => FileList.new("src/**/app/*.js") }
        jslint(config)
    end

That’s all you need.  Now you can run “rake lint” or tie this into to your existing process as you see fit.  Enjoy!

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