


How do I use the value attribute to specify the initial value of an input field?
Jun 24, 2025 am 12:44 AMIn HTML, the most straightforward way to set an initial value for the <input> field is to use the value attribute. 1. The basic usage is to specify the default display of the input box through value, which is suitable for text, password, email, number and other types, such as <input type="text" name="username" value="guest">; 2. It can be used for password boxes and number boxes, such as <input type="password" name="password" value="123456"> and <input type="number" name="age" value="18">; 3. Dynamically generate HTML in form backfill combined with PHP or JavaScript to retain the content that the user has filled in, such as , but be careful to prevent XSS attacks; 4. value is the initial value of the actual submission, while placeholder is the prompt text that will not be submitted. The two can be used together, such as .
In HTML, if you want to set an initial value for the <input>
field, the most direct way is to use value
attribute. This property allows you to specify the content displayed at the beginning of the input box, and is suitable for various types of input fields such as text boxes, password boxes, and digital inputs.
1. Basic usage: Set default values ??for text input boxes
The most common scenario is to set a default value to the text input box ( type="text"
). For example:
<input type="text" name="username" value="guest">
This code will display an input box when the page is loaded, and the default content is "guest". The user can modify this value, but if it is not changed, a "guest" will be sent when submitting the form.
- Applicable types : text, password, email, number, etc.
- Note : If the input box is empty, missing
value
attribute or leaving empty string will result in no default value.
2. Set the initial values ??of the password box and the number box
In addition to the text input box, you can also use value
to set other types of input fields. for example:
Password box:
<input type="password" name="password" value="123456">
Although hard-coded passwords in production environments are not recommended, it is convenient to write this way in tests or examples.
Digital input box:
<input type="number" name="age" value="18">
This initializes a numeric input box, with the default value of 18, and the user can only enter numbers.
3. Practical Tips for Using Value in Form Backfill
value
attribute is especially useful when you need to return an error message after processing form submission and retain what the user has filled in. For example, when dynamically generating HTML in PHP or JavaScript:
<input type="text" name="email" value="<?php echo isset($_POST['email']) ? $_POST['email'] : ''; ?>">
This way, even if the user submits it fails, they don't have to re-enter everything.
- Often used for frequent interactions such as registration, login, and search.
- Be careful to prevent XSS attacks and escape the output
4. The difference between placeholder is confused
Many people will confuse value
and placeholder
. Their differences are obvious:
-
value
is the actual initial value of the input box and will be submitted with the form -
placeholder
is just a prompt text and will not be submitted as a value. It will disappear after the user starts typing.
It works better when used correctly:
<input type="text" name="search" value="" placeholder="Please enter keywords">
Basically that's it. Rational use of value
attributes can improve user experience and simplify development processes. The key is to select the appropriate value according to the scene and pay attention to security and compatibility issues.
The above is the detailed content of How do I use the value attribute to specify the initial value of an input field?. For more information, please follow other related articles on the PHP Chinese website!

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