html input placeholder

Placeholder attribute does not exist for the <select> tag.
But there are some ways to make a placeholder for the select box.
The easiest way of making a placeholder for the <select> element is using the disabled and selected attributes with the HTML5 hidden global attribute.
  
<select name="monthname" required>
  <option value="" selected disabled hidden>Select Month</option>
  <option value="Jan">January</option>
  <option value="Feb">February</option>
  <option value="Mar">March</option>
  <option value="Apr">April</option>
  <option value="May">May</option>
  <option value="Jun">June</option>
  <option value="Jul">July</option>
  <option value="Aug">August</option>
  <option value="Sep">September</option>
  <option value="Oct">October</option>
  <option value="Nov">November</option>
  <option value="Dec">December</option>
</select>

input::-webkit-input-placeholder {/* Chrome/Opera/Safari/Edge */
	/*styles here*/
}

input::-ms-input-placeholder { /* Microsoft Edge */
   /*styles here*/
}

input:-ms-input-placeholder {/* IE 10+ */
	/*styles here*/
}

input::-moz-placeholder {/* Firefox 19+ */
	opacity: 1; /*Firefox by default has an opacity object that usually is ideal to reset so it matches webkit*/
	/*styles here*/
}

input:-moz-placeholder {/* Firefox 18- */
	opacity: 1; /*Firefox by default has an opacity object that usually is ideal to reset so it matches webkit*/
	/*styles here*/
}

input::placeholder {
	/*styles here*/
}

<form action="/action_page.php">
	<label for="phone">Enter a phone number:</label>
    <input type="tel" id="phone" name="phone" placeholder="123-45-678" pattern="[0-9]{3}-[0-9]{2}-[0-9]{3}"><br><br>
 </form> 
 

::placeholder {
  /*styles here*/
}

:-ms-input-placeholder { /* Internet Explorer 10-11 */
  /*styles here*/
}

document.querySelector('.gfield_list_cell.gfield_list_72_cell3 input').setAttribute('placeholder','$');