Adoption of JavaScript — and the Node.js runtime environment in particular — sets the stage for the biggest shift in enterprise application development in more than a decade. When building a technology platform to power their customer-facing web presence, enterprise development shops have generally chosen between two options, Java or .NET. The demands of mobile, particularly speed and scale of delivery and deployment, are fracturing this duopoly. New examples appear regularly of the retail site that was overloaded on Black Friday or the streaming app that stuttered when it went viral. This report examines how JavaScript addresses the scalability challenge, how it's changing both enterprise architectures and programming models, and what application development and delivery (AD&D) leaders should focus on during this transformative time.