LoopIteration - ComfyUI Built-in Node Documentation

This node provides iteration metadata for loop-style workflows. It receives list-based inputs and passes through the first element of each list, so a loop can track the current index, whether it is the first or last step, the current list item, and any running iteration value. Cache behavior is controlled by the reuse_cache flag. This node is marked as developer-only.

Inputs

Parameter	Description	Data Type	Required	Range
`iteration_index`	The index of the current iteration, supplied as a list. The first element is passed through to the output.	INT	Yes	-
`is_first`	Indicates whether the current iteration is the first one, supplied as a list. The first element is passed through to the output.	BOOLEAN	Yes	-
`is_last`	Indicates whether the current iteration is the last one, supplied as a list. The first element is passed through to the output.	BOOLEAN	Yes	-
`list_item`	The item taken from the list for this iteration. Optional; the first element is passed through to the output when provided, otherwise None is returned.	ANY	No	-
`current_iteration_value`	The value carried by the current iteration. Optional; when provided, the full value is passed through to the output, otherwise None is returned.	ANY	No	-
`reuse_cache`	Controls whether the result may be reused from cache. When enabled, the node keeps a stable fingerprint so cached results can be reused. When disabled, a non-matching fingerprint is produced so the node runs again on each iteration.	BOOLEAN	Yes	-

Note: This node is list-input enabled, meaning each input is expected to arrive as a list and the node outputs only the first element of each list (except current_iteration_value, which is passed through as a list). It also accepts additional inputs beyond those listed here.

Outputs

Output Name	Description	Data Type
`iteration_index`	The index of the current iteration.	INT
`is_first`	Whether the current iteration is the first one.	BOOLEAN
`is_last`	Whether the current iteration is the last one.	BOOLEAN
`list_item`	The item taken from the list for this iteration, or None when no item was provided.	ANY
`current_iteration_value`	The value carried by the current iteration, or None when no value was provided. This output is returned as a list.	ANY

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​Inputs

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Inputs

Outputs