语法
let collection = document.forms;
例子：获取表单信息
html
<html>
<head>
<title>document.forms example</title>
</head>
<body>
<form id="robby">
<input
type="button"
onclick="alert(document.forms[0].id);"
value="robby's form" />
</form>
<form id="dave">
<input
type="button"
onclick="alert(document.forms[1].id);"
value="dave's form" />
</form>
<form id="paul">
<input
type="button"
onclick="alert(document.forms[2].id);"
value="paul's form" />
</form>
</body>
</html>
例子：获取表单内的元素
js
var selectForm = document.forms[index];
var selectFormElement = document.forms[index].elements[index];