Format JavaScript Online

The file is parsed and then printed again from scratch, so the formatting you started with does not matter. Minified code, code with mixed tabs and spaces, and code that has passed through three editors all come out looking identical.

The controls cover the decisions that usually cause arguments in a codebase: indent width at two, four or eight spaces or tabs, print width at 60, 80, 100 or 120 columns, semicolons on or off, single or double quotes, trailing commas set to all, ES5 or none, arrow parentheses always or only when needed, and bracket spacing.

A diff view sits next to the formatted output and marks the lines that actually changed, with a count of additions and removals and the byte difference. That is the quickest way to confirm a reformat did not touch anything you cared about.