The required attribute is used to set fields that must be filled in in web forms. When using it, you can directly add the required keyword in the input tag; it can be used with various input types, textarea and select; it is also recommended to combine label to improve the user experience, and more complex verification rules can be achieved by cooperating with other verification attributes such as minlength, maxlength, pattern, etc.
Sometimes when you are making web forms, you will hope that users must fill in certain content. For example, the fields such as email and password when registering an account cannot be empty. HTML5 provides a simple and straightforward method: required attribute. After adding this attribute, the browser will automatically check whether these fields have been filled in when the user submits the form. If it is not filled in, it will also be prompted.
Basic usage: Add required attribute to input
The easiest way is to add the required keyword to the <input> tag you want to set as required. It does not require a value itself, and as long as it appears, it means that the field must be filled in.
For example:
<input type="text" name="username" required>
When the user submits a form, if the input box is empty, the browser will pop up a prompt telling you that this field cannot be left blank. Different browsers may have different prompt styles, but the basic functions are the same.
It should be noted that required can be used with various input types, such as text , email , password , number , etc., and can even be used on <textarea> and <select> .
Small details when using with placeholder
Many people like to add a placeholder prompt to the input box to tell the user what content should be filled in. for example:
<input type="email" name="email" placeholder="Please enter your email address" required>
But one thing to note: although placeholder has a hint, it is not a label. Some users may see the placeholder text and think it has been filled out, but they forget to enter it, which makes the form impossible to submit. Therefore, it is recommended to use it in conjunction with <label> to make the form structure clearer and the user experience better.
In addition, some browsers will only prompt common information such as "Please fill in this field" when verification fails, and will not repeat the content of placeholder . If you want the prompt information to be more specific, you can consider customizing the prompt with JavaScript, or using title attribute to provide additional instructions.
Use with other HTML5 verification properties
required is part of HTML5 form validation. It can also be used with other properties, such as minlength , maxlength , pattern , etc., to set more complex rules.
For example, if you want the user to enter a password with at least 6 digits, you can write it like this:
<input type="password" name="password" minlength="6" required>
For example, if you want to restrict users to only enter the mobile phone number format (assuming it is a domestic mobile phone number), you can use pattern with regular expressions:
<input type="text" name="phone" pattern="1[3-9]\d{9}" required>When these properties take effect at the same time, the browser will verify in order. In other words, first determine whether there is any filling, and then determine whether the length or format is correct.
- Required items must be filled in before continuing
- After filling in, it must meet the set format or length requirements.
- If it does not match, a prompt will also pop up to prevent the form from being submitted
The form made in this way is both concise and practical, and it does not require writing a line of JavaScript to achieve basic verification.
Basically that's it. Using the required attribute well can make front-end form verification much easier and improve the user's filling experience.
The above is the detailed content of Making Form Fields Mandatory Using the HTML5 Required Attribute. For more information, please follow other related articles on the PHP Chinese website!
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