一、Input 类型: tel
<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>test</title> 
</head>
<body><form action="demo-form.php">电话号码: <input type="tel" name="usrtel"><br><input type="submit">
</form></body>
</html>二、tel c++接口定义:
third_party\blink\renderer\core\html\forms\telephone_input_type.h
third_party\blink\renderer\core\html\forms\telephone_input_type.cc
namespace blink {class TelephoneInputType final : public BaseTextInputType {public:explicit TelephoneInputType(HTMLInputElement& element): BaseTextInputType(Type::kTelephone, element) {}private:void CountUsage() override;
};template <>
struct DowncastTraits<TelephoneInputType> {static bool AllowFrom(const InputType& type) {return type.IsTelephoneInputType();}
};}  // namespace blink三、看下tel构建堆栈:

