Be it through web parts, page layouts, or scoped custom actions, we've been able to inject client side JavaScript to SharePoint pages for quite some time. As your SharePoint platforms upgrade you may choose to undergo code conversion fit into the SharePoint Framework (SPFx). This session answers many questions surrounding the differences between web part/Custom Actions JavaScript injection tactics vs the SPFx. Doing so we will examine advantages and differences in use case, implementation scope, packaging and delivery of customizations made possible by two CDN centric, JavaScript injection methodologies, SPFx (2016 and beyond) and ScriptBlock Custom Actions (2013 and up).