HeEx Formatter

The HeEx Formatter accepts a raw HeEx template string and an optional set of formatting preferences. It normalizes indentation, wraps long attributes, and ensures consistent trailing spaces and line breaks. It understands Elixir expressions inside <%= %> blocks and does not change runtime semantics. The formatter is designed for Phoenix view templates and LiveView components; it helps teams adopt a shared style across template code. It is deterministic and idempotent: formatting the same input repeatedly yields identical output.
Under the hood, the tool performs a token-guided reflow: it tokenizes the template, tracks tags, attributes, and embedded Elixir, computes optimal line breaks based on max_line_length, and then reconstructs the code with standardized indentation. It preserves comments, HTML-like attributes, and notations such as assigns and liveview slots. Advanced options let you set indent sizes (2 or 4 spaces), a preferred maximum line length, and attribute wrapping strategy (wrap when necessary vs. align attributes).
Who benefits: Elixir developers, code reviewers, and teams maintaining Phoenix apps benefit from reduced review time, consistent aesthetics, and easier diff reviews. Unique value: domain-aware formatting for HeEx templates, support for LiveView constructs, and easy CI or pre-commit integration. Use cases include standardizing style before PRs, onboarding new contributors, and enforcing a team-wide code base standard without manual edits.