I'm trying to complete the basic python Selenium demo (https://selenium-python.readthedocs.io/getting-started.html) but I'm attempting to do that same procedure on https://www.ncbi.nlm.nih.gov/. However, it seems to be returning an empty list/it can't find the element. I tried to use the class_name but that also gave me an error because the class name has a space in it.

elem = driver.find_elements_by_class_name("typeahead tt-hint")
elem2 = driver.find_elements_by_xpath('//*[@id="main_content"]/section[1]/div/div[2]/div/form/div/span/input[1]')

Also, when doing the tutorial and trying the find_elements command on the different options <input id="id-search-field" name="q" type="search" role="textbox" class="search-field" placeholder="Search" value="" tabindex="1"> I don't quite understand why I seemed to get a type <class 'selenium.webdriver.remote.webelement.WebElement'>if I used elem = driver.find_element_by_name('q') and a <type 'list'> if I used anything else (xpath, id, class_name, etc).


  • 1
    Could you please tell which element on ncbi.nlm.nih.gov you are trying to locate? I don't see any element with class_name=typeahead or with id=main_content. Also, you can try locating with just class=typeahead instead of typeahead tt-hint. To your second question, you get WebElement when you use find_element and a list when you use find_elements.
    – Shamanth
    Commented Jan 21, 2019 at 3:33
  • Oh the element/elements issue makes sense, thanks so much! I was trying to locate the text box but I think that I may have been attempting to use to wrong tag/id? Anyway, I really appreciate the help!
    – Auraius
    Commented Jan 21, 2019 at 5:25

1 Answer 1


First of all, regarding your question about the return types of the "find" commands, it's quite straightforward:

  • find_element_by_*() methods return a WebElement instance - or, in other words, a single element
  • find_elements_by_*() methods return a list of WebElement instances - or, on other words, a list of elements

Now, let's look at what specific problems you have.

I am assuming you are working with this search page as I do see the text box you are talking about on this page. Let's look at this attempt you had to find the text box:

elem = driver.find_elements_by_class_name("typeahead tt-hint")

First of all, you need to use find_element_by_class_name() as you are looking for a single element only. Also, this locator only accept single class values - so, you could use either driver.find_element_by_class_name("typeahead"), or driver.find_element_by_class_name("tt-hint").

If you need to check both of the class values, you could use a CSS selector:


And, as we are looking for an input element, we could add the tag name check here as well:


But, as this element has an id element, you should just use "find element by id" strategy:

search_box = driver.find_element_by_id("search_term")
search_box.send_keys("my search query")

Make sure to look over this thread to get a better idea when to use what locator:

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