# Targeting Modern vs Legacy Browsers — Babel & SWC

Source: https://www.geekswithgeeks.com/en/babel-swc/bs-target-browser

> Adjust transpilation based on browser support requirements.

## Modern targets: less transpilation

If supporting only modern browsers (Chrome 90+, Firefox 88+), Babel skips most transpilation. Modern JavaScript features work natively, reducing bundle size.

## Browserslist examples

Use browserslist syntax to define targets. Preset-env reads this and transpiles accordingly.

```json
// Modern SPA: less transpilation
{
  "targets": {
    "browsers": ["last 2 Chrome versions", "last 2 Firefox versions"]
  }
}

// Legacy support: more transpilation
{
  "targets": {
    "browsers": ["IE 11", "iOS >= 9"]
  }
}
```

## Measure bundle impact

Transpiling for IE11 adds 20-30% to bundle size. For modern targets, you often skip transpilation entirely, saving kilobytes.