Cookbook for writing Sourcegraph extensions

Provide hover

// Imports the Sourcegraph extension API
import * as sourcegraph from "sourcegraph"

// Called by Sourcegraph when the extension is enabled by the user
export function activate(ctx: sourcegraph.ExtensionContext): void {
  // Shows a hello world message in a tooltip when the user hovers over code
  ctx.subscriptions.add(sourcegraph.languages.registerHoverProvider(["*"], {
    provideHover: () => ({ contents: { value: "Hello, world! πŸŽ‰πŸŽ‰πŸŽ‰" } })
  }))
}

Get the current document text

import * as sourcegraph from "sourcegraph"

export function activate(ctx: sourcegraph.ExtensionContext): void {
  ctx.subscriptions.add(sourcegraph.languages.registerHoverProvider(["*"], {
    provideHover: doc => ({ contents: { value: "Document size: " + doc.text.length } })
  }))
}

Change line background colors

import * as sourcegraph from "sourcegraph";

export function activate(ctx: sourcegraph.ExtensionContext): void {
  ctx.subscriptions.add(sourcegraph.workspace.onDidOpenTextDocument.subscribe(doc => {
    if (
      sourcegraph.app.activeWindow &&
      sourcegraph.app.activeWindow.visibleViewComponents.length > 0
    ) {
      sourcegraph.app.activeWindow.visibleViewComponents[0].setDecorations(
        null,
        [
          {
            // The top line (base 0)
            range: new sourcegraph.Range(
              new sourcegraph.Position(0, 0),
              new sourcegraph.Position(0, 0)
            ),
            backgroundColor: "magenta"
          }
        ]
      );
    }
  }));
}

Add an annotation after the end of a line

import * as sourcegraph from "sourcegraph";

export function activate(ctx: sourcegraph.ExtensionContext): void {
  ctx.subscriptions.add(sourcegraph.workspace.onDidOpenTextDocument.subscribe(doc => {
    if (
      sourcegraph.app.activeWindow &&
      sourcegraph.app.activeWindow.visibleViewComponents.length > 0
    ) {
      sourcegraph.app.activeWindow.visibleViewComponents[0].setDecorations(
        null,
        [
          {
            range: new sourcegraph.Range(
              new sourcegraph.Position(0, 0),
              new sourcegraph.Position(0, 0)
            ),
            after: {
              contentText: " View on npm (" + downloads + " DLs last week)",
              linkURL: `https://www.npmjs.com/package/${pkg}`,
              backgroundColor: "pink",
              color: "black"
            }
          }
        ]
      );
    }
  }));
}

Read/write settings

import * as sourcegraph from "sourcegraph";

export function activate(): void {
  const address = sourcegraph.configuration.get().get("graphql.langserver-address");
  if (!address) {
    console.log("No graphql.langserver-address was set, exiting.");
    return;
  }
  // ...
}