Output-centric programming paradigms such as Direct Manipulation Programming, Programming By Demonstration, and Programming By Example enable users to author programs by constructing an intended output. However, sometimes the purpose of a programming interaction is to discover an “intended output” in the first place (e.g., exploratory data analysis, improvisational creative coding, early-stage prototyping). We argue that one role for output-centric programming here is scaffolding the user in demonstrating their next program editing step by selecting among possible modifications to their current program. We call this Programming By Scaffolded Demonstration (PBSD). To explore PBSD, we built Perpend, a programming environment for p5.js. In a user study with nine artists, we juxtapose Perpend with an existing Direct Manipulation editor, exploring how participants used Perpend to situate themselves within a space of possible programs, shift focus between program text and visual output, and shape their exploration by modifying their program structure.