Indent generated content

Indent a block of generated content to match the code around it.

Rendered from docs/how-to/indent-generated-content.md in the generator repository — where a correction belongs, and where the test suite runs every example on this page or states why it does not.

Generated code that lands at column zero inside a nested block is correct and unreadable. Content, Line and Fragment all take an indent prop: a number of spaces, or a literal prefix string.

import { Jostraca, Project, File, Content } from 'jostraca'

const body = 'const a = 1\nconst b = 2\n'

await Jostraca().generate({ folder: './out' }, () => {
  Project({}, () => {
    File({ name: 'fn.js' }, () => {
      Content('export function go() {\n')
      Content({ src: body, indent: 2 })
      Content('}\n')
    })
  })
})

The generated fn.js:

export function go() {
  const a = 1
  const b = 2
}

indent applies to every line start in the block, so a multi-line string arrives already aligned. A string value is used verbatim, which covers tabs and comment prefixes: indent: '\t', or indent: '// ' to comment a block out.

Two edges to know:

A blank line inside the block is indented too, which leaves trailing whitespace on it. Strip it afterwards if your linter cares.
A trailing newline gets nothing appended after it, so the block ends cleanly rather than with a stray indent.

Inside a List, indent is passed to each child rather than applied by the list itself. The child has to forward it:

import { Jostraca, Project, File, Content, List } from 'jostraca'

const items = [{ name: 'alpha' }, { name: 'beta' }]

await Jostraca().generate({ folder: './out' }, () => {
  Project({}, () => {
    File({ name: 'list.txt' }, () => {
      List({ item: items, indent: 2, line: false }, ({ replace, indent }) => {
        Content({ src: '{item.name}\n', replace, indent })
      })
    })
  })
})

The generated list.txt:

  alpha
  beta

Indent generated content

See also#