45. What are presets in Babel and how do you use them?

Presets in Babel are collections of plugins that are configured to perform specific transpilation tasks. A preset is the simplest way to configure Babel, allowing for the transformation of JavaScript code using predefined sets of plugins.

Popular presets:

1. @babel/preset-env: Transforms modern JavaScript to ES5-compatible code, automatically adjusting configuration based on target browsers.
2. @babel/preset-react: Transforms JSX and other React-specific syntax.
3. @babel/preset-typescript: Transforms TypeScript code to JavaScript.

How to use presets:

1. Installing presets:

npm install --save-dev @babel/preset-env

2. Configuring the .babelrc file:

{
  "presets": ["@babel/preset-env"]
}

3. Transpiling code with Babel:

npx babel src --out-dir lib

Presets simplify Babel configuration, allowing you to quickly start using modern JavaScript without the need to manually set up multiple plugins.