jquery adds readonly

When developing front-end pages, it is sometimes necessary to set certain form elements to readonly status to prevent users from misoperation or malicious tampering with data. jQuery is a popular JavaScript library that allows us to implement front-end pages more efficiently and conveniently. This article will introduce how to use jQuery to add the readonly attribute to form elements.

1. What is the readonly attribute?

The readonly attribute is usually used to limit the input range of form elements. When a form element is set to read-only status, users cannot modify it and can only view the value of the element. This is useful for displaying certain sensitive data or restricting user actions.

In HTML, we can achieve read-only status by setting the readonly attribute on the form element. For example:

<input type="text" name="username" value="johndoe" readonly>

In the above code snippet, a text box named "username" is set to read-only status, and "johndoe" is displayed in the input box by default. When the user tries to modify the content in the input box, it will not take effect.

2. How to use jQuery to set the readonly attribute

Different from native HTML attributes, you need to use the prop() method to modify the attribute value in jQuery. prop() accepts two parameters, the first parameter is the name of the attribute to be modified, and the second parameter is the value to be assigned to the attribute. For read-only properties, we need to set the second parameter to true or false to control whether it is read-only.

For example, the following code snippet sets an input box named "password" to a read-only state:

$('[name="password"]').prop('readonly', true);

In the above code, we first use jQuery's selector to locate An input box named "password", and then set the readonly attribute to true through the prop() method to achieve read-only status. If we want to cancel the read-only state, we only need to set the second parameter to false.

3. Use the attr() method to set the readonly attribute

In early versions of jQuery, the attr() method was usually used to modify the attribute value of an HTML element. Although the prop() method is more commonly used than the attr() method, if you are using an older version of jQuery, you can use the attr() method to set the readonly attribute.

For example, the following code snippet sets an input box named "phone" to a read-only state:

$('[name="phone"]').attr('readonly', true);

Similar to the prop() method, we can also use the attr() method The second parameter is set to false to cancel the read-only state.

4. Conclusion

In front-end development, sometimes we need to set certain form elements to read-only status to prevent users from misoperation or malicious tampering with data. This can be achieved more easily using jQuery. In this article, we introduced how to set the readonly attribute using jQuery's prop() and attr() methods. Whether you are using a new version of jQuery or an old version of jQuery, you can choose the method that suits you according to your needs.

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