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                <form class="container" id="needs-validation" novalidate>
  <div class="row">
    <div class="col-md-6 mb-3">
      <label for="input-name">Name</label>
      <input type="text" class="form-control" name="name" id="input-name" placeholder="Name" required>
      <div class="invalid-feedback"></div>
  <div class="row">
    <div class="col-md-6 mb-3">
      <label for="input-email">Email</label>
      <input type="email" class="form-control" name="email" id="input-email" placeholder="" required>
      <div class="invalid-feedback"></div>
  <div class="row">
    <div class="col-md-6 mb-3">
      <label for="input-message">Message</label>
      <textarea class="form-control" name="message" id="input-message" required maxlength="100" placeholder="最大100文字"></textarea>
      <div class="message-text-counter">現在<span class="message-text-count">0</span>文字</div>
      <div class="invalid-feedback"></div>
  <button class="btn btn-primary" type="submit">Submit</button>




                $(function() {
var $form = $("#needs-validation"),
    $inputs = $form.find('.form-control'),
    $email = $inputs.find('[name=name]'),
    $message = $inputs.find('[name=message]'),
    $content_text_counter = $form.find('.message-text-count');
    $form.on("submit", function(event) {
      if ( == false) {
    $inputs.on('change, keyup', function () {
      if($(this).is('[name=message]')) {
        var count = countTxtLength($(this).val());

var feedbackMessage = {}; = {
  valueMissing: '名前を入力してください',
}; = {
  valueMissing: 'メールアドレスを入力してください',
  typeMismatch: '不正なメールアドレスです'
feedbackMessage.message = {
  valueMissing: 'メッセージを入力してください',
  tooLong: '文字数が長すぎます'

//@param {JQuery} $inputs .form-control elements array
function validation($inputs) {
  $inputs.each(function(i, el) {
    var $el = $(el);
    var id = $el.attr('id').replace('input-', '');
    var validity = el.validity;
    var $feedback = $el.find('~ .invalid-feedback');
    var message = feedbackMessage[id];
    $.each(message, function(i, mes) {
      if(validity[i] === true) {

//@param value {string} 数える文字列
//@param mode {number} 0=全部1 1=半角0.5 全角1
function countTxtLength(value, mode) {
  var count = 0, mode = mode || 0;

  for(var i = value.length; i--; ) {
    if(mode === 1 && /^[\u0020-\u007e]+$/.test(value.charAt(i))) {
      count += 0.5;
    } else {
      count += 1;

  return count;

 var _feedbackMessageSample = {
   //ユーザーがUIが値に変換できない入力をした場合に true
  badInput: '',
  //要素の値が与えられたパターンにマッチしない場合に true
  patternMismatch: '',
  //要素の値が与えられた最大値を超える場合に true
  rangeOverflow: '',
  //要素の値が与えられた最小値を下回る場合に true
  rangeUnderflow: '',
  //要素の値が step 属性で与えられた規則に合わない場合に true
  stepMismatch: '',
  //要素の値が与えられた長さより長い場合に true
  tooLong: '',
  //要素の値が与えられた長さより短い場合に true
  tooShort: '',
  //要素の値が正しい構文ではない場合に true
  typeMismatch: '',
  //要素が入力必須のフィールドであるのに値がない場合に true
  valueMissing : ''