All Objects
Select Object
PROPERTY: Select::options
object.
options
The
options
property is an array of all the options in a particular
Select
object. There is one element (numbered in ascending order from zero) for each <OPTION> tag. You can use the
length
property of this array to refer to the number of options in a particular
Select
object as follows:
Code:
document.myForm.mySelect.options.length
...or by simply using the
length
property of the
Select
object:
Code:
document.myForm.mySelect.length
You can use the
options
array to add options to, or delete options from any
Select
object. When adding or altering an option, you assign an
Option
object to a particular element of the array. The following code first creates an
Option
object called Folk, and then assigns it to element # 3 of the
options
array of a user-defined
Select
object called MusicType. If there is a value already assigned to element 3, it will be replaced by Folk, otherwise it will be created along with undefined elements at every index between the one created and the last existant one.
Code:
document.forms[0].musicType.options[3] = new Option("Folk", "folk", false, false)
Similarly, you can delete any option by assigning the value
null
to the appropriate element of the
options
array:
Code:
document.forms[0].musicType.options[2] = null
This will have the effect of removing element # 2 from the
options
array, and at the same time compressing the array so that element # 3 becomes # 2, element # 4 becomes # 3 etc. After deleting an option you must refresh the document by using
history.go(0)
at the end of the code. To determine which option of a
Select
object is currently selected, you can use the
selectedIndex
property along with the
options
property as follows:
Code:
document.forms[0].musicType.options.selectedIndex
...or you could simply use the
selectedIndex
property of the
Select
object:
Code:
document.forms[0].musicType.selectedIndex
Both the above lines of code return the number of the currently-selected index. If, however, the
Select
object allows for multiple selections (i.e. when the <SELECT> tag includes the MULTIPLE attribute), the
selectedIndex
property will only return the index of the first option selected. To determine all of the selected options, you would have to loop through the
options
array testing each option individually.
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