tessl/npm-ejs

Embedded JavaScript templates for generating HTML markup with plain JavaScript.

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Overview

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Command Line Interface

Name: tessl/npm-ejs
Author: tessl

EJS provides a comprehensive command-line interface for rendering templates directly from the terminal, supporting various input methods, output options, and template configuration.

Capabilities

CLI Command

The EJS CLI is installed as a global command when the package is installed.

# Basic usage
ejs [options ...] template-file [data variables ...]

# Installation provides the 'ejs' command
npm install -g ejs

Usage Examples:

# Render template with data file
ejs ./template.ejs -f ./data.json

# Render with inline data variables
ejs ./template.ejs name=John age=30

# Render with custom delimiters and output to file
ejs -m $ ./template.ejs -f ./data.json -o ./output.html

# Pipe data via stdin
echo '{"name": "Alice"}' | ejs ./template.ejs

# Remove whitespace and use custom delimiters
ejs -w -p [ -c ] ./template.ejs -o ./output.html

CLI Options

The CLI supports extensive configuration options for template rendering:

# Output Options
-o, --output-file FILE            Write rendered output to FILE rather than stdout
-f, --data-file FILE              Use JSON-formatted input from FILE as data
-i, --data-input STRING           Use JSON-formatted URI-encoded STRING as data

# Delimiter Options
-m, --delimiter CHARACTER         Use CHARACTER with angle brackets (defaults to %)
-p, --open-delimiter CHARACTER    Use CHARACTER instead of left angle bracket
-c, --close-delimiter CHARACTER   Use CHARACTER instead of right angle bracket

# Template Options
-s, --strict                      Generate function in strict mode
-n, --no-with                     Use 'locals' object instead of 'with' statement
-l, --locals-name NAME            Name for object storing local variables
-w, --rm-whitespace               Remove all safe-to-remove whitespace
-d, --debug                       Output generated function body

# Help Options
-h, --help                        Display help message
-V, -v, --version                 Display EJS version

Data Input Methods

The CLI supports multiple ways to provide data to templates, in order of precedence:

# 1. Stdin (highest precedence)
echo '{"title": "Hello"}' | ejs template.ejs

# 2. Inline data input via -i flag
ejs template.ejs -i '{"title":"Hello"}'

# 3. Data file via -f flag
ejs template.ejs -f data.json

# 4. Individual variables (lowest precedence, but override others)
ejs template.ejs title="Hello" name="World"

Data Input Rules:

Only one input method can be used (stdin, -i, or -f)
Individual variables always override values from other sources
All data must be JSON-formatted (except individual variables)
URI encoding required for -i flag data

Delimiter Configuration

Customize template syntax using delimiter options:

# Use $ instead of % (produces <$ $> tags)
ejs -m $ template.ejs -f data.json

# Use square brackets instead of angle brackets
ejs -p [ -c ] template.ejs -f data.json
# Produces [% %] syntax

# Combine both for custom syntax
ejs -m @ -p { -c } template.ejs -f data.json  
# Produces {@ @} syntax

Template Processing Options

Control template compilation and output:

# Strict mode - disables 'with' statement
ejs -s template.ejs -f data.json

# No-with mode - uses locals object instead of 'with'
ejs -n template.ejs -f data.json

# Custom locals name with no-with
ejs -n -l customLocals template.ejs -f data.json

# Remove whitespace for minified output
ejs -w template.ejs -f data.json

# Debug mode - shows generated JavaScript
ejs -d template.ejs -f data.json

Output Control

Direct rendered output to files or stdout:

# Output to stdout (default)
ejs template.ejs -f data.json

# Output to specific file
ejs template.ejs -f data.json -o output.html

# Chain with other commands
ejs template.ejs -f data.json | gzip > output.html.gz

Error Handling

The CLI provides clear error messages for common issues:

# Missing template file
$ ejs
Error: Please provide a template path. (Run ejs -h for help)

# Multiple data input methods
$ echo '{}' | ejs template.ejs -f data.json
Error: Please do not pass data multiple ways. Pick one of stdin, -f, or -i.

# Invalid JSON data
$ ejs template.ejs -f invalid.json
SyntaxError: Unexpected token in JSON

# Template file not found
$ ejs missing.ejs
Error: ENOENT: no such file or directory, open 'missing.ejs'

Version and Help

Get version information and usage help:

# Display version
ejs --version
# or
ejs -V
# or  
ejs -v

# Display help with all options
ejs --help
# or
ejs -h

Advanced Usage Examples

Complex CLI usage patterns for various scenarios:

# E-commerce template with product data
ejs -w ./templates/product.ejs -f ./data/products.json -o ./dist/products.html

# Email template with custom delimiters to avoid conflicts
ejs -m @ ./email-template.ejs name="John" email="john@example.com"

# Debug template compilation
ejs -d ./complex-template.ejs -f ./test-data.json > debug-output.js

# Batch processing with variables
for user in alice bob charlie; do
  ejs ./user-template.ejs name="$user" -o "./output/${user}.html"
done

# Pipeline processing with JSON data
curl -s https://api.example.com/data | ejs ./api-template.ejs -o result.html

# Custom locals name for conflict avoidance
ejs -n -l templateData ./template.ejs -f ./data.json

Integration with Build Tools

Common patterns for integrating EJS CLI with build systems:

# npm scripts in package.json
{
  "scripts": {
    "build:templates": "ejs -w ./src/template.ejs -f ./data/config.json -o ./dist/index.html",
    "dev:watch": "chokidar './src/**/*.ejs' -c 'npm run build:templates'"
  }
}

# Makefile integration
build:
	ejs -w ./templates/layout.ejs -f ./config/prod.json -o ./public/index.html

# Shell script automation
#!/bin/bash
for template in ./templates/*.ejs; do
  name=$(basename "$template" .ejs)
  ejs -w "$template" -f "./data/${name}.json" -o "./output/${name}.html"
done

Install with Tessl CLI