Where multiple controls exist, radio buttons allow one to be selected out of them all, whereas checkboxes allow multiple values to be selected. The value attribute is a DOMString 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. A radio group is defined by giving each of radio buttons in the group the same name.
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 name. For example, if your form needs to ask the user for their preferred contact method, you might create three radio buttons, each with the name property set to contact but one with the value email , one with the value phone , and one with the value mail.
The user never sees the value or the name unless you expressly add code to display it. Here you see the three radio buttons, each with the name set to contact and each with a unique value that uniquely identifies that individual radio button within the group.
If you omit the value attribute in the HTML, the submitted form data assigns the value on to the group. So don't forget to set your value 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 checked state.
See Selecting a radio button by default below. You can use any of them. However, they also have few differences like performance and size of code, etc. Let's see some difference between them:. The code written with getElementById is a bit longer than the querySelector.
Using the getElementById method, we need to check each radio button individually which one is checked. On the other side, if you use the querySelector DOM method, you just have to put a single line of code to check the marked radio button and get its value. So, the conclusion is that querySelector requires less code. Both functions provide good performance but all you need to know which one is better.
The getElementById method is much faster than the querySelector method. The querySelector method is a bit complex, as well. The getElementById method always uses a unique id of each radio button while checking the marked button and returns the first element matches with the id. Whereas querySelector uses a common name selector for all radio buttons to get the marked radio button and returns the first element that matches with the specified selector.
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Copyright by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3. Specifies whether a radio button should be checked or not.
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