Dom选择器使用与调试记录

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="#12">我喜欢学习python</div>
    <a>123</a>
    <a>456</a>
    <a>789</a>

</body>
</html>

document.getElementById('#12')
<div id="#12">我喜欢学习python</div>
document.getElementById('#12').innerText
"我喜欢学习python"
document.getElementById('#12').innerText="我也超级喜欢"
"我也超级喜欢"
document.getElementsByTagName('a')[1]
<a>456</a>
document.getElementsByTagName('a')[1].innerText='qwe'
"qwe"
msg = document.getElementsByTagName('a')
HTMLCollection(3) [a, a, a]
for(var i=0;i<msg;i++){msg[i].innerText=111}
undefined
for(var i=0;i<msg;i++){msg[i].innerText=111;}
undefined
for(var i=0;i<msg.length;i++){msg[i].innerText=111}
111