elements of type are generally used in radio groups—collections of radio buttons describing a set of related options.
Only one radio button in a given group can be selected at the same time. Radio buttons are typically rendered as small circles, which are filled or highlighted when selected.
They are called radio buttons because they look and operate in a similar manner to the push buttons on old-fashioned radios, such as the one shown below.
Note:Checkboxes are similar to radio buttons, but with an important distinction: radio buttons are designed for selecting one value out of a set, whereas checkboxes let you turn individual values on and off. Where multiple controls exist, radio buttons allow one to be selected out of them all, whereas checkboxes allow multiple values to be selected.
The attribute is a containing the radio button's value. The value is never shown to the user by their user agent. Instead, it's used to identify which radio button in a group is selected.
Defining a radio group
A radio group is defined by giving each of radio buttons in the group the same . Once a radio group is established, selecting any radio button in that group automatically deselects any currently-selected radio button in the same group.
You can have as many radio groups on a page as you like, as long as each has its own unique .
For example, if your form needs to ask the user for their preferred contact method, you might create three radio buttons, each with the property set to but one with the value , one with the value , and one with the value . The user never sees the or the (unless you expressly add code to display it).
The resulting HTML looks like this:
Here you see the three radio buttons, each with the set to and each with a unique that uniquely identifies that individual radio button within the group. They each also have a unique , which is used by the element's attribute to associate the labels with the radio buttons.
You can try out this example here:
Data representation of a radio group
When the above form is submitted with a radio button selected, the form's data includes an entry in the form . For example, if the user clicks on the "Phone" radio button then submits the form, the form's data will include the line .
If you omit the attribute in the HTML, the submitted form data assigns the value to the group. In this scenario, if the user clicked on the "Phone" option and submitted the form, the resulting form data would be , which isn't helpful. So don't forget to set your attributes!
Note: If no radio button is selected when the form is submitted, the radio group is not included in the submitted form data at all, since there is no value to report.
It's fairly uncommon to actually want to allow the form to be submitted without any of the radio buttons in a group selected, so it is usually wise to have one default to the state. See Selecting a radio button by default below.
Let's add a little bit of code to our example so we can examine the data generated by this form. The HTML is revised to add a block to output the form data into:
Try this example out and see how there's never more than one result for the group.
In addition to the common attributes shared by all elements, inputs support the following attributes.
A Boolean attribute which, if present, indicates that this radio button is the default selected one in the group.
Unlike other browsers, Firefox by default persists the dynamic checked state of an across page loads. Use the attribute to control this feature.
The attribute is one which all s share; however, it serves a special purpose for inputs of type : when a form is submitted, only radio buttons which are currently checked are submitted to the server, and the reported value is the value of the attribute. If the is not otherwise specified, it is the string by default. This is demonstrated in the section Value above.
Using radio inputs
We already covered the fundamentals of radio buttons above. Let's now look at the other common radio-button-related features and techniques you may need to know about.
Selecting a radio button by default
To make a radio button selected by default, you include attribute, as shown in this revised version of the previous example:
In this case, the first radio button is now selected by default.
Note: If you put the attribute on more than one radio button, later instances will override earlier ones; that is, the last radio button will be the one that is selected. This is because only one radio button in a group can ever be selected at once, and the user agent automatically deselects others each time a new one is marked as checked.
Providing a bigger hit area for your radio buttons
In the above examples, you may have noticed that you can select a radio button by clicking on its associated element, as well as on the radio button itself. This is a really useful feature of HTML form labels that makes it easier for users to click the option they want, especially on small-screen devices like smartphones.
Beyond accessibility, this is another good reason to properly set up elements on your forms.
Radio buttons don't participate in constraint validation; they have no real value to be constrained.
Styling radio inputs
The following example shows a slightly more thorough version of the example we've seen throughout the article, with some additional styling, and with better semantics established through use of specialized elements. The HTML looks like this:
There's not much new to note here except for the addition of and elements, which help to group the functionality nicely and in a semantic way.
The CSS involved is a bit more significant:
Most notable here is the use of the property (with prefixes needed to support some browsers). By default, radio buttons (and checkboxes) are styled with the operating system's native styles for those controls. By specifying , you can remove the native styling altogether, and create your own styles for them. Here we've used a along with and a to create a nice animating radio selection. Notice also how the pseudo-class is used to specify the styles for the radio button's appearance when selected.
Note: If you wish to use the property, you should test it very carefully. Although it is supported in most modern browsers, its implementation varies widely. In older browsers, even the keyword does not have the same effect across different browsers, and some do not support it at all. The differences are smaller in the newest browsers.
Notice that when clicking on a radio button, there's a nice, smooth fade out/in effect as the two buttons change state. In addition, the style and coloring of the legend and submit button are customized to have strong contrast. This might not be a look you'd want in a real web application, but it definitely shows off the possibilities.
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Vehicle-Inside Phase-Stable Fiber-Optics Network for Distributing Reference Radio-Frequency Signals
Abstract: An advanced high quality and cost-efficient approach to solve an issue of phase distortion in onboard fiber-optic network delivering a set of reference radio-frequency signals is proposed and demonstrated using a wavelength division multiplexing technique. The basic distortions in analog fiber-optics link with an emphasis on the key sources of phase errors such as phase noise, jitter, and wander are reviewed. The approach is experimentally validated during field tests in realistic aircraft environment.
Published in: 2020 International Topical Meeting on Microwave Photonics (MWP)
Date of Conference: 24-26 Nov. 2020
Date Added to IEEE Xplore: 12 January 2021
Electronic ISBN: 978-4-88552-331-1
Print on Demand(PoD) ISBN: 978-1-7281-9849-1
1.1.Book with one author
1.2.Book with two or three authors
1.3.Book with more than three authors
1.4.Book with an author and an editor
1.5.Entire Edited Book
1.6.Chapter/Section in an Edited Book
1.7. Translated book
1.8. Book that is part of a multi-volume set
1.9. The Sacred Texts
1.10. Dictionary / Encyclopedia Entry
1.11. Book Review
1.12. Foreword, Afterword, Epigraph, Epilogue
3.1. Journal Article
3.2. Newspaper / Magazine Article
3.3. Pre-print / In-press Article
4. Official Publications
4.1. Acts of Parliament
5. Unpublished Material
5.1. Conference paper
5.2. Thesis / Dissertation
6. Audio/-Visual Material
6.2. Television Programme
6.2.1. Single TV Programme
6.2.2. Episode of a TV Programme/Series
6.3. Radio Programme
6.4. Image (photos, illustrations, diagrams, tables, etc.)
6.5. Oral History
6.6. Graphic Novels
6.7. Music Track
8. Social Media(Tweets, Facebook Posts, etc.)
1. Speech transcript
- Provide the name of the speaker as the author.
- If the transcript and original work were published in different years (e.g., in the transcript of an old speech, as shown in the example), provide the year of the transcript in the main date element of the reference and the year of the original work in parentheses at the end of the reference.
- Provide both years in the in-text citation, separated with a slash, the earlier year first.
- Describe the type of transcript in square brackets (e.g., “[Speech transcript]”).
- Provide the site name in the source element of the reference, followed by the URL of the transcript.
- For an example reference to a speech’s audio recording, see Example 96 in the Publication Manual.
2. Podcast transcript
- The format for a podcast transcript is nearly the same as for a podcast episode (see Example 94 in the Publication Manual). The only difference is that the description after the transcript title is “[Audio podcast transcript]” rather than “[Audio podcast].”
- Provide the name of the host of the podcast as the author and include their role in parentheses.
- Provide the specific date of the podcast.
- Provide the episode number after the title in parentheses. If the podcast does not number episodes, omit the number from the reference.
- Provide the name of the site that published the transcript (in the examples, NPR and Gimlet Media) and the URL of the transcript.
3. Radio broadcast transcript
- The format for a radio broadcast transcript is nearly the same as for a radio broadcast. The only difference is that the description after the transcript title is “[Radio broadcast transcript]” rather than “[Radio broadcast].”
- Provide the name of the announcer as the author.
- Provide the full date of the radio broadcast.
- Provide the title of the story in italics, followed by the description “[Radio broadcast transcript].”
- Provide the name of the site that published the radio broadcast (in the example, ABC) and the URL of the broadcast. In the example, both the radio recording and the transcript are available from the same link, so that link appears in the reference.
Date created: February 2020
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