Javascript : Selectors
document.getElementById("rob")
document.getElementsByClassName("rob")
document.getElementsByTagName("li")
document.querySelector(".rob")
document.querySelector("#rob")
document.querySelectorAll(".rob") //returns array
document.querySelectorAll(".#rob") //returns array
jQuery
$("#theForm") // by id
$(".button-blue") // by class
$("li") // by tag
$("[name='foo']") //by name
$("input:checked" ) // by checked