验证 html 中的输入文本字段

Question

Suppose:

There's First Name: (box for input first name)

Requirement: i cannot left this field empty,error message should generate if i left it empty.

Solve this only through HTML

Answer 1

<input> has a required attribute, as such:

<input type="text" name="username" required>

This will raise an error if the user tries to submit the form without first filling out the input. That being said, please google this next time.

W3Schools Page

Answer 2

<form>
first name <input type="text" name="firstname" required>
<input type="submit">
</form>