PortalJS — Add Chart

Overview

Add a visualization to a dataset's showcase in a PortalJS portal. The skill installs recharts (added directly — never @portaljs/components), writes a reusable client-side Chart component into components/, and renders a <Chart /> into the Views section of the showcase route pages/[owner]/[slug].tsx for one chosen dataset. The chart reads the same /public/data/<file> the showcase <Table /> already uses, so no data is duplicated. Five chart types are supported: line, bar, area, pie, and scatter.

Prerequisites

A scaffolded PortalJS portal (see portaljs-new-portal).
The target dataset already registered in datasets.json (see portaljs-add-dataset).
components/ui/parseCsv.ts present (ships with the template).
Node 18+ and npm available in the portal directory.

Instructions

The canonical, full step-by-step workflow is .claude/commands/portaljs-add-chart.md — the single source of truth. Read and follow it when executing. Summary:

Gather input — dataset slug, X column, Y column(s), chart type (default line), portal directory. If any is missing, interview the user; never dead-end on a missing value.
Resolve the dataset from datasets.json (namespace, file, format).
Validate that the X and every Y column exist in the data file's header; warn on non-numeric Y columns (values are coerced with Number()).
Install the chart library: npm install recharts@^2.15.0.
Write components/Chart.tsx (idempotent — do not overwrite a customized component).
Render <Chart /> into the Views section, gated on the dataset's (namespace, slug) so other showcases are unaffected. Extend an existing view-dispatch block, do not overwrite.
Verify with npx tsc --noEmit.
Report the component, route, and dependency added.

Output

Created: components/Chart.tsx (recharts wrapper, if absent).
Modified: pages/[owner]/[slug].tsx (import + gated <Chart /> in Views); package.json (recharts@^2.15.0).
UI strings: any text it adds to JSX renders through t() (lib/i18n.ts), with the keys added to locales/en.json and every other locales/*.json; npm run i18n:check passes.
Verified: npx tsc --noEmit passes.
Result: the chart renders at /@<namespace>/<slug> under a "Views" heading.

Error Handling

Symptom	Cause	Fix
Missing dataset/columns	Slug or column not in manifest/header	List available slugs/headers and re-prompt; do not error out.
Gaps in the chart	Non-numeric cells coerced to `NaN`	Clean the source data or pick a numeric Y column.
`tsc` failure	Bad column prop or import path	Fix the first reported error before reporting success.
Sluggish render	Over ~2,000 SVG points	Pre-aggregate the series (e.g. yearly buckets).

Examples

Example 1 — Single line series

/portaljs-add-chart co2-emissions x=year y=emissions type=line

Example 2 — Multi-series bar chart

/portaljs-add-chart trade x=year y=imports,exports type=bar

Example 3 — Pie chart of a categorical breakdown

/portaljs-add-chart budget x=department y=amount type=pie

Resources

Full workflow: .claude/commands/portaljs-add-chart.md
Chart-type and prop reference: references/reference.md
Related skills: portaljs-add-dataset, portaljs-add-map, portaljs-define-schema
recharts documentation: https://recharts.org/