buuh/packages/html/server.js

// Ported from nanohtml 1.10.0 lib/server.js (MIT) — https://github.com/choojs/nanohtml
// Server-side tagged template: renders straight to an escaped HTML string.
// The browserify/babel transform branches of the original are gone for good —
// this is a pure runtime tag.

const BOOL_PROPS = [
  'async', 'autofocus', 'autoplay', 'checked', 'controls', 'default',
  'defaultchecked', 'defer', 'disabled', 'formnovalidate', 'hidden',
  'ismap', 'loop', 'multiple', 'muted', 'novalidate', 'open', 'playsinline',
  'readonly', 'required', 'reversed', 'selected'
]

const boolPropRx = new RegExp('([^-a-z](' + BOOL_PROPS.join('|') + '))=["\']?$', 'i')
const query = /(?:="|&)[^"]*=$/

export default function html (pieces, ...values) {
  let boolMatch
  let output = ''
  for (let i = 0; i < pieces.length; i++) {
    const piece = pieces[i]
    if (i < pieces.length - 1) {
      if ((boolMatch = boolPropRx.exec(piece))) {
        output += piece.slice(0, boolMatch.index)
        if (values[i]) {
          output += boolMatch[1] + '="' + boolMatch[2] + '"'
        }
        continue
      }

      const value = handleValue(values[i])
      if (piece[piece.length - 1] === '=' && !query.test(piece)) {
        output += piece + '"' + value + '"'
      } else {
        output += piece + value
      }
    } else {
      output += piece
    }
  }

  // HACK: Avoid double encoding by marking encoded string
  // You cannot add properties to string literals
  // eslint-disable-next-line no-new-wrappers
  const wrapper = new String(output)
  wrapper.__encoded = true
  return wrapper
}

function handleValue (value) {
  // Handle each item in array as potential unescaped value
  if (Array.isArray(value)) return value.map(handleValue).join('')

  // Ignore event handlers. `onclick=${(e) => doSomething(e)}`
  // will become.           `onclick=""`
  if (typeof value === 'function') return ''
  if (value === null || value === undefined) return ''
  if (value.__encoded) return value

  if (typeof value === 'object') {
    if (typeof value.outerHTML === 'string') return value.outerHTML
    return Object.keys(value).reduce(function (str, key) {
      if (str.length > 0) str += ' '

      if (BOOL_PROPS.indexOf(key) !== -1) {
        if (value[key]) {
          return str + key + '="' + key + '"'
        }
        return str
      }

      const handled = handleValue(value[key])
      return str + key + '="' + handled + '"'
    }, '')
  }

  const str = value.toString()
  return str
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#039;')
}

export { html }