taro-sockjs-client/src/transport/sender/jsonp.js

sockjs-client for Taro

import random from '../../utils/random'
import urlUtils from '../../utils/url'
import debug from '../../utils/debug'

let form, area

function createIframe(id) {
  debug('createIframe', id)
  try {
    // ie6 dynamic iframes with target="" support (thanks Chris Lambacher)
    return global.document.createElement('<iframe name="' + id + '">')
  } catch (x) {
    let iframe = global.document.createElement('iframe')
    iframe.name = id
    return iframe
  }
}

function createForm() {
  debug('createForm')
  form = global.document.createElement('form')
  form.style.display = 'none'
  form.style.position = 'absolute'
  form.method = 'POST'
  form.enctype = 'application/x-www-form-urlencoded'
  form.acceptCharset = 'UTF-8'

  area = global.document.createElement('textarea')
  area.name = 'd'
  form.appendChild(area)

  global.document.body.appendChild(form)
}

export default function (url, payload, callback) {
  debug(url, payload)
  if (!form) {
    createForm()
  }
  let id = 'a' + random.string(8)
  form.target = id
  form.action = urlUtils.addQuery(
    urlUtils.addPath(url, '/jsonp_send'),
    'i=' + id,
  )

  let iframe = createIframe(id)
  iframe.id = id
  iframe.style.display = 'none'
  form.appendChild(iframe)

  try {
    area.value = payload
  } catch (e) {
    // seriously broken browsers get here
  }
  form.submit()

  let completed = function (err) {
    debug('completed', id, err)
    if (!iframe.onerror) {
      return
    }
    iframe.onreadystatechange = iframe.onerror = iframe.onload = null
    // Opera mini doesn't like if we GC iframe
    // immediately, thus this timeout.
    setTimeout(function () {
      debug('cleaning up', id)
      iframe.parentNode.removeChild(iframe)
      iframe = null
    }, 500)
    area.value = ''
    // It is not possible to detect if the iframe succeeded or
    // failed to submit our form.
    callback(err)
  }
  iframe.onerror = function () {
    debug('onerror', id)
    completed()
  }
  iframe.onload = function () {
    debug('onload', id)
    completed()
  }
  iframe.onreadystatechange = function (e) {
    debug('onreadystatechange', id, iframe.readyState, e)
    if (iframe.readyState === 'complete') {
      completed()
    }
  }
  return function () {
    debug('aborted', id)
    completed(new Error('Aborted'))
  }
}