Editors

tern lsp is a language server for Tern apps, beside gopls and the Svelte language server. It knows what they don't: which Go load a page's data comes from, the app's routes, and the types of Go components. Extensions for VS Code and Zed start it; any editor with LSP can.

• Page ⇄ load: go to definition on data, form, PageProps or LayoutProps in a page or layout opens its Go load; on Load, LayoutLoad or Actions in the Go file, the component. On the pattern in route('/blog/[slug]'), that route's page. Elsewhere it answers nothing, so the editor's other servers answer.
• Routes: the app's routes are workspace symbols, such as /blog/[slug]: Cmd+T or Ctrl+T finds them.
• tern check: when a file is saved, or changes outside the editor, it runs code generation and tern check, and shows their errors in the files they're in. A check takes a few seconds, so it runs on save rather than as you type; the Svelte and Go servers still check as you type.
• Code lenses: a link at the top of each page to its load, and above each load to its page, in editors that show them.

It runs as go tool tern lsp, in the project, so it's the project's own version of Tern.

#VS Code

The extension is in editors/vscode. Build and install it:

cd editors/vscode
npm install
npm run package
code --install-extension tern-0.1.0.vsix

Besides the language server, it adds a Routes view to the Explorer, and Alt+O to go between a page and its load. Use it with the Svelte and Go extensions. tern.server sets the command it starts.

#Zed

The extension is in editors/zed. In Zed, run zed: install dev extension and choose that folder; Zed builds it, with Rust installed. Use it with the Svelte extension.

To run another command than go tool tern lsp:

{
  "lsp": {
    "tern": { "binary": { "path": "tern", "arguments": ["lsp"] } }
  }
}

#Other editors

Start go tool tern lsp in the project, for Svelte, Go and TypeScript files, next to the other servers. In Neovim:

vim.lsp.config('tern', {
  cmd = { 'go', 'tool', 'tern', 'lsp' },
  filetypes = { 'svelte', 'go', 'typescript' },
  root_markers = { 'go.mod' },
})
vim.lsp.enable('tern')

In Helix, in languages.toml:

[language-server.tern]
command = "go"
args = ["tool", "tern", "lsp"]

[[language]]
name = "svelte"
language-servers = ["svelteserver", "tern"]