Readonly lengthlength
number of elements in the array.
GetElementAt()
Retrieve a specific element of the array. null is a valid result for this method.
Note: If the index is out of bounds null will be returned. This differs from the behavior of nsIArray.queryElementAt() which will throw if an invalid index is specified.
position of element
Optional aInstancePtr: objectA run time mechanism for interface discovery.
NS_OK if the interface is supported by the associated instance, NS_NOINTERFACE if it is not.
aInstancePtr must not be null.
[in] A requested interface IID
[out] A pointer to an interface pointer to receive the result.
enumerate the array
a new enumerator positioned at the start of the array
NS_ERROR_FAILURE if the array is empty (to make it easy to detect errors), or NS_ERROR_OUT_OF_MEMORY if out of memory.
indexOf()
Get the position of a specific element. Note that since null is a valid input, exceptions are used to indicate that an element is not found.
a number >= startIndex which is the position of the element in the array.
NS_ERROR_FAILURE if the element was not in the array.
The initial element to search in the array To start at the beginning, use 0 as the startIndex
The element you are looking for
queryElementAt()
Retrieve a specific element of the array, and QueryInterface it to the specified interface. null is a valid result for this method, but exceptions are thrown in other circumstances
NS_ERROR_NO_INTERFACE when an entry exists at the specified index, but the requested interface is not available.
NS_ERROR_ILLEGAL_VALUE when index > length-1
position of element
the IID of the requested interface
the object, QI'd to the requested interface
Generated using TypeDoc
Helper interface for allowing scripts to treat nsIArray instances as if they were nsISupportsArray instances while iterating.
nsISupportsArray is convenient to iterate over in JavaScript:
for (let i = 0; i < array.Count(); ++i) { let elem = array.GetElementAt(i); ... }
but doing the same with nsIArray is somewhat less convenient, since queryElementAt is not nearly so nice to use from JavaScript. So we provide this extension interface so interfaces that currently return nsISupportsArray can start returning nsIArrayExtensions and all JavaScript should Just Work. Eventually we'll roll this interface into nsIArray itself, possibly getting rid of the Count() method, as it duplicates nsIArray functionality.