@printedjs/plugin-eta

Pre-pagination template compilation plugin for Printedjs powered by Eta.

Enables dynamic data evaluation, variable interpolation, conditional rendering, loops, and custom helper functions prior to document layout.

Features

• Fast Embedded Templates — Full Eta template engine support with <% %> script tags, <%= %> escaped output, and <%- %> raw output.
• Built-in Helpers — Pre-registered helpers for dates (dayjs), numbers (numeral), currencies, casing, and array aggregations.
• Safe Evaluation Context — Scoped property proxy blocking accidental prototype leaks or unwanted global access.
• BigInt & JSON Normalization — Deep type conversion ensuring compatibility with standard numbers and structured records.

Installation

pnpm add @printedjs/plugin-eta @printedjs/core

Usage

As a Printedjs Plugin

import { createRenderer } from "@printedjs/browser";
import { etaPlugin } from "@printedjs/plugin-eta";

const renderer = createRenderer({
	target: document.querySelector("#preview")!,
	plugins: [
		etaPlugin({
			data: {
				invoiceNumber: "INV-2025-001",
				customer: { name: "Acme Corp" },
				items: [
					{ name: "Widgets", amount: 150 },
					{ name: "Gadgets", amount: 250 },
				],
			},
		}),
	],
});

Standalone Template Compilation

import { compileTemplate, renderTemplate } from "@printedjs/plugin-eta";

const template = `
  <h1>Invoice #<%= invoiceNumber %></h1>
  <p>Customer: <%= customer.name %></p>
  <ul>
    <% items.forEach(item => { %>
      <li><%= item.name %> - <%= format(item.amount) %></li>
    <% }) %>
  </ul>
`;

const data = {
	invoiceNumber: "INV-042",
	customer: { name: "John Doe" },
	items: [{ name: "Hosting", amount: 49 }],
};

const output = renderTemplate(template, data);
console.log(output);

Configuration Options

| Option | Type | Default | Description | | :-------- | :------------------------- | :----------------------- | :--------------------------------------------------- | | data | Record<string, unknown> | {} | Context data provided to template variables | | helpers | Record<string, Function> | defaultTemplateHelpers | Custom helper functions accessible in template scope | | useWith | boolean | true | Exposes context keys directly as local variables |