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![Julieta Dalla Pozza](https://uploads.teamtreehouse.com/production/profile-photos/11655513/micro_Screen_Shot_2021-03-03_at_21.13.34.jpg)
Julieta Dalla Pozza
4,337 PointsSelect elements by id or class
Hi, i am a lil confused here. Sometimes to get an element by id you need to put # or if is a class you need a dot but sometimes you don't. Don't get it much when is necessary and when is no?
2 Answers
![Steven Parker](https://uploads.teamtreehouse.com/production/profile-photos/969492/micro_tool_chess_set_2.jpg)
Steven Parker
230,688 PointsFunctions that are simple and only take one kind of argument (like getElementById and getElementsByClassName) use only the name.
But querySelector (and querySelectorAll) takes a complex argument which works like a selector in CSS. So it uses the CSS syntax to indicate what kind of thing it is looking for where an ID is preceded by "#", and a class by ".".
![Tony Idehen](https://secure.gravatar.com/avatar/9cba1d3d5f88196b7b0d5c7738886c31?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
Tony Idehen
8,059 PointsThe document.querySelector(selectors) and document.querySelectorAll(selectors) uses the CSS selectors, so the selectors must be written as represented or be written in CSS(i.e # before the Id name, .(dot) before the class name , h2 or img ). My understanding, the getElementById(idname) and getElementsByClassName(classname) are specifically asking for elements with id or classname. Hence you give only the names as written in html. You don't need to add the dot(.) or # before the names.