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template()

template(template, data): string

Replaces {key} placeholders in a string with values from a data object.

💎 Why is this a Hidden Gem?

Lightweight string interpolation with support for nested paths ({user.name}). No regex complexity, no external dependencies.

note

Supports nested paths ({user.name}). Use {{ and }} for literal braces. Missing keys become empty strings.

Parameters​

template: string​

The template string with {key} placeholders.

data: Record<string, unknown> = {}​

The data object containing values.

Returns: string​

The interpolated string.

Since​

2.0.0

Performance​

O(n × m) time where n is template length, m is max path depth. Single regex pass with reduce for nested paths.

Also known as​

template (Lodash, es-toolkit, Radashi, Antfu) · ❌ (Remeda, Ramda, Effect, Modern Dash)

Example​

template('Hello {name}', { name: 'World' });
// => 'Hello World'

template('{user.name} <{user.email}>', {
  user: { name: 'John', email: 'john@example.com' }
});
// => 'John <john@example.com>'

template('Literal: {{escaped}}', {});
// => 'Literal: {escaped}'

How it works?​

Replaces {key} placeholders with values from a data object. Supports nested paths.

Nested Paths​

Escape Braces​

Use {{ and }} for literal braces.

Missing Keys​

Missing keys become empty strings.

Use Cases​

Interpolate dynamic strings 📌​

Replace placeholders in a string with data values. Perfect for localization (i18n) or generating dynamic messages.

const msg = template('Welcome, {user.name}!', { user: { name: 'Alice' } });
// 'Welcome, Alice!'

Render email notifications​

Build transactional email bodies from templates and user data. Avoids manual string concatenation and keeps templates readable.

const emailBody = template(
  'Hi {name}, your order #{orderId} has been {status}. Track it at {trackingUrl}.',
  { name: 'Alice', orderId: '8842', status: 'shipped', trackingUrl: 'https://track.example.com/8842' }
);
// 'Hi Alice, your order #8842 has been shipped. Track it at https://track.example.com/8842.'

Format error messages with context​

Inject runtime context into error message templates for clearer debugging.

const errorTemplates = {
  NOT_FOUND: 'Resource {resource} with id {id} not found.',
  RATE_LIMIT: 'Rate limit exceeded for {endpoint}. Retry after {retryAfter}s.',
};

const msg = template(errorTemplates.NOT_FOUND, { resource: 'User', id: '42' });
// 'Resource User with id 42 not found.'