dropdown icon button bootstrap code example

Example 1: navbar bootstrap 4 with dropdown

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#">Disabled</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

Example 2: dropdowns

There are 2 dropdowns
1- HTML
2- SELECT

we determine what kind of dropdown it is
 -By tagName.We inspect.If it has <select> tag, it means it is <select> dropdown. 
 -If it is HTML, we can locate and click just as any other web element.
 
 I handle Select type of dropdown by using Select class from Selenium. 
    - Methods to select from dropdown:
        - selectByVisibleText
        - selectByValue
        - selectByIndex 
        
I verify which option is selected in a dropdown?
 - If we want to get the currently selected option, 
 we use getFirstSelectedOption() method.
        -> return type: currently selected option as a web element
        
--> .getOptions();
    -> This method will return all of the options in the <select> web element.
    -> return type: List<WebElement>