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C # tutorial
Select Object : Find out how many options there are in a specific drop-down list
The options collection returns a collection of all <option> elements in a drop-down list.
Collection | |||||
---|---|---|---|---|---|
options | Yes | Yes | Yes | Yes | Yes |
Property | Description |
---|---|
length | Returns the number of <option> elements in the collection. Note: This property is read-only |
selectedIndex | Sets or returns the index of the selected <option> element in the collection (starts at 0) |
Method | Description |
---|---|
[index] | Returns the <option> element from the collection with the specified index (starts at 0). Note: Returns null if the index number is out of range |
[add(option[,index])] | Adds an <option> element into the collection at the specified index. If no index is specified, it inserts the option at the end of the collection |
item(index) | Returns the <option> element from the collection with the specified index (starts at 0). Note: Returns null if the index number is out of range |
namedItem(id) | Returns the <option> element from the collection with the specified id. Note: Returns null if the id does not exist |
remove(index) | Removes the <option> element with the specified index from the collection |
DOM Version: | Core Level 2 Document Object |
---|---|
Return Value: | An HTMLOptionsCollection Object, representing all <option> elements in the <select> element. The elements in the collection are sorted as they appear in the source code |
[index]
Get the text of the first option (index 0) in a drop-down list:
var x = document.getElementById("mySelect").options[0].text;
The result of x will be:
Apple
item(index)
Get the text of the first option (index 0) in a drop-down list:
var x = document.getElementById("mySelect").options.item(0).text;
The result of x will be:
Apple
namedItem(id)
Get the text of the option with id="orange" in a drop-down list:
var x = document.getElementById("mySelect").options.namedItem("orange").text;
The result of x will be:
Orange
Add a "Kiwi" option at index position "1" in a drop-down list:
var x = document.getElementById("mySelect");
var c = document.createElement("option");
c.text = "Kiwi";
x.options.add(c, 1);
Remove the option with index "1" from a drop-down list:
var x = document.getElementById("mySelect");
x.options.remove(1);
Loop through all options in a drop-down list, and output the text of each option:
var x = document.getElementById("mySelect");
var txt = "";
var i;
for (i = 0; i < x.length; i++) {
txt = txt + x.options[i].text + "<br>";
}
The result of txt will be:
Apple
Orange
Pineapple
Banana
Choose an option in the drop-down list and output the text of the selected option in an element with id="demo":
var x = document.getElementById("mySelect");
var i = x.selectedIndex;
document.getElementById("demo").innerHTML = x.options[i].text;
The result could be:
Banana
Change the options in a drop-down list depending on the selected option in another drop-down list:
var carsAndModels = {};
carsAndModels['VO'] = ['V70', 'XC60', 'XC90'];
carsAndModels['VW'] = ['Golf', 'Polo', 'Scirocco', 'Touareg'];
carsAndModels['BMW'] = ['M6', 'X5', 'Z3'];
function ChangeCarList() {
var carList = document.getElementById("car");
var modelList = document.getElementById("carmodel");
var selCar = carList.options[carList.selectedIndex].value;
while (modelList.options.length) {
modelList.remove(0);
}
var cars = carsAndModels[selCar];
if (cars) {
var i;
for (i = 0; i < cars.length; i++) {
var car = new Option(cars[i], i);
modelList.options.add(car);
}
}
}
❮ Select Object