// 选择<p>JavaScript</p>:

var js = document.querySelector('#test-p');

// 选择<p>Python</p>,<p>Ruby</p>,<p>Swift</p>:

var arr = document.getElementById("test-div").getElementsByClassName("c-red c-green")[0].children;

// 选择<p>Haskell</p>:

var haskell = document.getElementsByClassName("c-green")[1].lastElementChild;