kristerkari/placekeeper

import * as utils from "./utils.js"

const supportedElementTypes = [
  "text",
  "search",
  "url",
  "tel",
  "email",
  "password",
  "number",
  "textarea"
]

// The list of keycodes that are not allowed when the polyfill is configured
// to hide-on-input.
const badKeys = [

  // The following keys all cause the caret to jump to the end of the input
  // value.

  27, // Escape
  33, // Page up
  34, // Page down
  35, // End
  36, // Home

  // Arrow keys allow you to move the caret manually, which should be
  // prevented when the placeholder is visible.

  37, // Left
  38, // Up
  39, // Right
  40, // Down

  // The following keys allow you to modify the placeholder text by removing
  // characters, which should be prevented when the placeholder is visible.

  8, // Backspace
  46 // Delete
]

// Opera Mini v7 doesn't support placeholder although its DOM seems to indicate so
const isOperaMini = Object.prototype.toString.call(window.operamini) === "[object OperaMini]"

function isElementSupported(element) {
  return "placeholder" in document.createElement(element) && !isOperaMini
}

export function isInputSupported() {
  return isElementSupported("input")
}

export function isTextareaSupported() {
  return isElementSupported("textarea")
}

export function hasNativePlaceholderSupport() {
  return isInputSupported() || isTextareaSupported()
}

// Avoid IE9 activeElement of death when an iframe is used.
//
// More info:
// - http://bugs.jquery.com/ticket/13393
// - https://github.com/jquery/jquery/commit/85fc5878b3c6af73f42d61eedf73013e7faae408
export function safeActiveElement() {
  /*eslint-disable no-empty */
  try {
    return document.activeElement
  } catch (ex) {}
  /*eslint-enable no-empty */
}

export function isSupportedType(elementType) {
  return utils.inArray(supportedElementTypes, elementType)
}

export function isBadKey(keyCode) {
  return utils.inArray(badKeys, keyCode)
}

function isIE9() {
  const ie9 = /MSIE 9/i
  return ie9.test(window.navigator.userAgent)
}

export function canChangeToType(elem, type) {
  // IE9 can change type from password to text,
  // but not back from text to password.
  if (isIE9()) {
    return false
  }
  // Input type can not be changed in IE8 and below.
  try {
    const oldType = elem.type
    elem.type = type
    elem.type = oldType
    return true
  } catch(ex) {
    return false
  }
}

export function needsToShowPlaceHolder(elem) {
  return utils.hasPlaceholderAttrSet(elem) && isSupportedType(utils.getElementType(elem))
}