xxxxxxxxxx<html><head><meta charset="utf-8"> <title>W3Cschool(w3cschool.cn)</title> </head><body><form action="/statics/demosource/demo-form.php" id="numform" oninput="x.value=parseInt(a.value)+parseInt(b.value)">0<input type="range" id="a" name="a" value="50">100+<input type="number" id="b" name="b" value="50"><br><br><input type="submit"></form><p> element 元素在表单之外,但它仍属于该表单的一部分。</p><output form="numform" name="x" for="a b"></output><p><b>注意:</b>几乎所有的主流浏览器都不支持 form 属性。</p></body></html>