Support html5 placeholder attribute for IE without using jquery or any dependencies.

ie-placeholder.js

window.initPlaceHolder = (textField) => {
  const addEvent = document.addEventListener ? 'addEventListener' : 'attachEvent';
  const eventPrefix = document.addEventListener ? '' : 'on';
  const placeHolderClassName = 'usingPlaceHolder';
  const $trim = (string) => {
    return string.trim ? string.trim() : string.replace(/^\s+|\s+$/g, "");
  };
  const $addClassName = (element, className) => {
    var elClassName = element.className;
    if(elClassName)
      element.className += " " + className;
    else
      element.className = className;
  };
  const $removeClassName = (element, className) => {
    let elClassName = element.className;
    if ( !elClassName ) {
      return;
    }
    element.className = elClassName.replace(new RegExp("(^|\\s+)" + className + "(\\s+|$)"), ' ');
  };
  const $hasClassName = (element, className) => {
    let elClassName = element.className;
    if( !elClassName ) {
      return false;
    }
    const regex = new RegExp("(^|\\s)" + className + "(\\s|$)");
    return regex.test(element.className);
  };

  if('placeholder' in document.createElement('input')) {
    return;
  }

  let placeHolder = textField.getAttribute('placeholder');
  if( !placeHolder ) {
    return;
  }

  placeHolder = $trim(placeHolder);

  if ( placeHolder === '' ) {
    return;
  }

  const onBlur = () => {
    if ( textField.value !== '' ) {
      return;
    }
    textField.value = placeHolder;
    $addClassName(textField, placeHolderClassName);
  };

  textField[addEvent](eventPrefix + 'blur', onBlur, false);
  textField[addEvent](eventPrefix + 'focus', () => {
    if ( $hasClassName(textField, placeHolderClassName) ) {
      $removeClassName(textField, placeHolderClassName);
      textField.value = "";
    }
  }, false);

  const form = textField.form;
  if ( form ) {
    form[addEvent](eventPrefix + 'submit', () => {
      if ( $hasClassName(textField, placeHolderClassName) ) {
        textField.value = '';
      }
    }, false);
  }
  onBlur();
};