Gradle build script to install NodeJS packages and Bower dependencies. This assumes you create package.json (nodejs) and bower.json files in the root of your project.

build.gradle

import org.gradle.api.tasks.Exec

defaultTasks 'bower'

// Get the path for the locally installed binaries
task npmBin << {
    new ByteArrayOutputStream().withStream { os ->
        def result = exec {
            executable = 'npm'
            args = ['bin']
            standardOutput = os
        }
        ext.binPath = os.toString().trim() + "/"
    }
}


// Install packages from package.json
task npm(type: Exec) {
    description = "Grab NodeJS dependencies (from package.json)"
    commandLine = ["npm", "install"]
    inputs.file "package.json"
    outputs.dir "node_modules"

    tasks.npmBin.execute()

}


// Install the bower components for front-end library management
task bower(dependsOn: 'npm', type: Exec){
    commandLine "${npmBin.binPath}bower", 'install'
}

Thanks for the initial code to solve this problem. We ran into issues on Windows and have found an OK work-around :) https://gist.github.com/pacey/54278ecd716e82b16f14