Comprehensive Guide to cli-highlight

The cli-highlight library is a powerful tool for developers who need to add syntax highlighting to their command line interface (CLI) applications. This guide introduces you to several APIs provided by cli-highlight and demonstrates how you can use these APIs to build impressive CLI applications.

Installing cli-highlight

First, you need to install cli-highlight using npm:

npm install cli-highlight

Basic Usage

Here is a simple example of how to use cli-highlight to highlight a block of code:

const { highlight } = require('cli-highlight');

const code = `
const hello = 'world';
console.log(hello);
`;

console.log(highlight(code, { language: 'javascript' }));

Available Options

There are several options available for customizing the highlighting:

• language: Specifies the language of the code. If not set, it tries to auto-detect.
• ignoreIllegals: Whether to ignore illegal syntax (default: false).
• theme: Custom theme for syntax highlighting.

Highlighting Multiple Languages

You can specify the language explicitly or let cli-highlight auto-detect the language:

console.log(highlight(code, { language: 'javascript' }));
console.log(highlight(code2));  // Auto-detects the language

Using Custom Themes

You can customize the colors and styles used for highlighting with themes:

const customTheme = {
  keyword: ['yellow', 'bold'],
  string: ['green'],
  built_in: ['blue'],
};

console.log(highlight(code, { language: 'javascript', theme: customTheme }));

CLI Application Example

Here’s an example of a CLI application that takes user input, detects the language, and highlights the syntax in the output:

const { highlight, getLanguage } = require('cli-highlight');
const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

console.log('Enter code:');

rl.on('line', (input) => {
  const language = getLanguage(input) || 'plaintext';
  console.log(highlight(input, { language }));
});

In this example, we used getLanguage to auto-detect the language of the user input before highlighting it.

With these examples and explanations, you should now be ready to use cli-highlight to build your own sophisticated CLI applications that feature syntax highlighting.

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