diff --git a/.lighthouse/pipeline-format.yaml b/.lighthouse/pipeline-format.yaml
index 4493a79..e53d3ef 100644
--- a/.lighthouse/pipeline-format.yaml
+++ b/.lighthouse/pipeline-format.yaml
@@ -143,6 +143,44 @@ spec:
         params:
           - name: docker-image
             value: "$(params.image-name):$(tasks.fetch-repository.results.commit)"
+      - name: run-prettier
+        taskSpec:
+          metadata: {}
+          params:
+            - name: docker-image
+              type: string
+              description: Docker image to run.
+              default: alpine:3.18
+          stepTemplate:
+            image: alpine:3.18
+            name: ""
+            resources:
+              requests:
+                cpu: 10m
+                memory: 600Mi
+            workingDir: /workspace/source
+          workspaces:
+            - name: source
+              mountPath: /source
+          steps:
+            - name: run
+              image: $(params.docker-image)
+              workingDir: "$(workspaces.source.path)"
+              command: ["sh", "-c"]
+              args:
+                - |
+                  prettier --write --no-error-on-unmatched-pattern "default_environment/**/*.js" "default_environment/**/*.css"
+              env:
+                - name: CARGO_TARGET_DIR
+                  value: /target
+        workspaces:
+          - name: source
+            workspace: git-source
+        runAfter:
+          - run-cargo-fmt
+        params:
+          - name: docker-image
+            value: "$(params.image-name):$(tasks.fetch-repository.results.commit)"
       - name: commit-changes
         taskRef:
           resolver: git
@@ -173,7 +211,7 @@ spec:
           - name: source
             workspace: git-source
         runAfter:
-          - run-cargo-fmt
+          - run-prettier
     finally:
       - name: report-success
         when:
diff --git a/docker/natter_development/Dockerfile b/docker/natter_development/Dockerfile
index a217814..bfbcdb1 100644
--- a/docker/natter_development/Dockerfile
+++ b/docker/natter_development/Dockerfile
@@ -3,3 +3,8 @@ FROM rustlang/rust:nightly-alpine3.17 AS builder
 RUN apk add --no-cache musl-dev
 RUN cargo install --locked --no-default-features --features ci-autoclean cargo-cache
 RUN rustup component add rustfmt
+
+FROM builder AS javascript
+
+RUN apk add --no-cache npm
+RUN npm install --global prettier@3.1.0