# Using list tags in ECMAScript

You can write ECMAScript functions that manipulate the
values in a multi-value tag. The Java™ ArrayList
class is available for multi-value tags in custom functions that you
write in HCL OneTest™ API. Not all methods are guaranteed to work.

For general information about scripting, see Scripts within tests and stubs.

In the following example script, the `numbers.get()` method
returns the value corresponding to the specified index, and the `numbers.add()` method
appends a new value to the list.

```
// Get the last two numbers in the list, and convert them to numbers:
var beforePrevious = parseInt(numbers.get(numbers.size() - 2));
var previous = parseInt(numbers.get(numbers.size() - 1));
// Add 10 more numbers to the list
for(var i=0; i<10; i++) {
// Calculate the next number to add to the list
var next = beforePrevious + previous;
// Add it to the list
numbers.add(next);
// Update the variables for calculating the next number
beforePrevious = previous;
previous = next;
}
```