change the value must be message in text field javascript code example

Example 1: change input required text html

<input type="text" id="username" required placeholder="Enter Name"
    oninvalid="this.setCustomValidity('Enter User Name Here')"
    oninput="this.setCustomValidity('')"  />

Example 2: how to collect input textbox in html

<label for="name">Name:</label>
  <input type="text" id="name"><br><br>