Ensuring the User Provides a Value

You do this with the required attribute. The user cannot submit the form until a value has been provided.

 
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
</head>
<body>
      <form method="post" action="http://yourServer/form">
            <input type="hidden" name="recordID" value="1234" />
            <p>
                  <label for="name"> Name: <input type="text" required
                        id="name" name="name" />
                  </label>
            </p>
            <p>
                  <label for="password"> Password: <input type="password"
                        required placeholder="Min 6 characters" id="password"
                        name="password" />
                  </label>
            </p>
            <p>
                  <label for="accept"> <input type="checkbox" required
                        id="accept" name="accept" /> Accept Terms & Conditions
                  </label>
            </p>
            <input type="submit" value="Submit" />
      </form>
</body>
</html>

Click to view this demo.

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Input Validation:

Using Input Validation
Ensuring the User Provides a Value
Ensuring a Value Is Within Bounds
Ensuring a Value Matches a Pattern
Ensuring a Value Is an E-mail Address or URL
Disabling Input Validation