js method to use DOM to set radio buttons, check boxes and drop-down menus

The example in this article describes how js uses DOM to set radio buttons, check boxes and drop-down menus. Share it with everyone for your reference. The specific implementation method is as follows:

The radio button in the form is It is a set of objects for the user to select, but only one can be selected at a time. Each one has a checked attribute. When one selection is true, the others become false.
As can be seen from the above code, the id and name are different. Their names in a group of radio buttons are the same, and only one is selected. The id is bound to or other selection effects.

In the code: the code to check the selected object is (when the chcked value of a certain item is true, the traversal ends)

var oForm = document.forms["uForm1"];
var aChoices = oForm.camera;
for (i = 0; i < aChoices.length; i ) //Traverse the entire single-choice list
If (aChoices[i].checked) //Exit if the selected item is found
break;
alert("The camera brand is: " aChoices[i].value);

Unlike radio buttons, checkboxes can select multiple options for processing at the same time. The checkbox before each email in the mailbox is a typical use

The check box principle is determined by using the Boolean value of the checked attribute. Parameters can be passed in the form of 0 and 1 to select all and not all.

3. Drop-down menu

Drop-down menu. When the drop-down menu is for multiple selection, when multiple="multiple", its function is equivalent to that of a check box, but it occupies less area. Much smaller than a checkbox.

Common attributes of drop-down menus:

Properties	Description
length	Indicates the number of options
selected	Boolean value, indicating whether
SelectedIndex	The serial number of the selected option, -1 if no option is selected. For multi-select drop-down menus, return the first selected option Serial number, counting from 0
text	Text of option
value	Option value
type	The type of drop-down menu, single selection returns select-one, multiple selection returns select-multiple
options	Get the array of options, for example: oSelectBox.options[2], which represents the third item of the drop-down menu oSelectBox