HTMLAllCollection
Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
The HTMLAllCollection
interface represents a collection of all of the document's elements, accessible by index (like an array) and by the element's id
. It is returned by the document.all
property.
HTMLAllCollection
has a very similar shape to HTMLCollection
, but there are many subtle behavior differences — for example, HTMLAllCollection
can be called as a function, and its item()
method can be called with a string representing an element's id
or name
attribute.
Instance properties
HTMLAllCollection.length
Read only-
Returns the number of items in the collection.
Instance methods
HTMLAllCollection.item()
-
Returns the element located at the specified offset into the collection, or the element with the specified value for its
id
orname
attribute. Returnsnull
if no element is found. HTMLAllCollection.namedItem()
-
Returns the first element in the collection whose
id
orname
attribute match the given string name, ornull
if no element matches.
Usage in JavaScript
Indexed access
In addition to the methods above, elements in an HTMLAllCollection
can be accessed by integer indices and string property names. The HTML id
attribute may contain :
and .
as valid characters, which would necessitate using bracket notation for property access. collection[i]
is equivalent to collection.item(i)
, where i
can be an integer, a string containing an integer, or a string representing an id
.
Calling as a function
An HTMLAllCollection
object is callable. When it's called with no arguments or with undefined
, it returns null
. Otherwise, it returns the same value as the item()
method when given the same arguments.
Special type conversion behavior
For historical reasons, document.all
is an object that in the following ways behaves like undefined
:
- It is loosely equal to
undefined
andnull
. - It is falsy in boolean contexts.
- Its
typeof
is"undefined"
.
These special behaviors ensure that code like:
if (document.all) {
// Assume that we are in IE; provide special logic
}
// Assume that we are in a modern browser
Will continue to provide modern behavior even if the code is run in a browser that implements document.all
for compatibility reasons.
However, in all other contexts, document.all
remains an object. For example:
- It is not strictly equal to either
undefined
ornull
. - When used on the left-hand side of the nullish coalescing operator (
??
) or the optional chaining operator (?.
), it will not cause the expression to short-circuit.
Specifications
Specification |
---|
HTML Standard # the-htmlallcollection-interface |
Browser compatibility
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