Loop

The Loop node makes a sub-workflow execute repeatedly. Four loop modes are supported.

Overview

After filling in the loop name, the node automatically generates two loop variables for use inside the loop body:

• {{loopName.index}} — the current iteration index (starting from 0)
• {{loopName.value}} — the current iteration value

The node has two output ports: Body connects the loop body (executes on each iteration), and Completed connects downstream nodes after the loop ends.

Loop state (index, queue, watermark) is persisted between iterations and survives page refreshes without losing progress.

Usage

After dragging in the node, first fill in "Loop Name," then select the loop mode.

Count Mode

Iterates from a start number to an end number one by one. Internal logic: start + index; continues while currentValue < endValue.

Note: The end value is exclusive (similar to Python's range), not "less than or equal."

Loop Name: i, Start: 1, End: 3
Iteration 1: i.index=0, i.value=1  (1 < 3 ✓)
Iteration 2: i.index=1, i.value=2  (2 < 3 ✓)
Loop ends                           (3 < 3 ✗)

Best for "repeat N times" scenarios.

Array Mode

Iterates over each element of an array. The array content is entered in JSON5 format, parsed and placed into a consumption queue. Each iteration takes one element from the front of the queue (shift); the loop ends when the queue is empty.

Loop Name: user, Array: ["Alice", "Bob", "Charlie"]
Initial queue: ["Alice", "Bob", "Charlie"]
Iteration 1: user.index=0, user.value="Alice"   (queue: ["Bob", "Charlie"])
Iteration 2: user.index=1, user.value="Bob"     (queue: ["Charlie"])
Iteration 3: user.index=2, user.value="Charlie" (queue: [])
Loop ends

Best for "do the same thing to each element in a list" scenarios.

Variable Mode

References an upstream variable for iteration. The strategy is auto-selected based on the variable type:

• Variable is a number (e.g., 5): Executes in count mode — index from 0 to N-1, value equals index. Continues while index < variableValue.
• Variable is an array or other: Executes in incremental queue mode. Only newly appearing elements are added to the consumption queue (deduplicated via a globalCursor watermark). Already-consumed elements are not processed again.

# Numeric variable
Loop Name: i, Variable Reference: {{count}}  (count = 3)
Iteration 1: i.index=0, i.value=0
Iteration 2: i.index=1, i.value=1
Iteration 3: i.index=2, i.value=2
Loop ends

# Array variable
Loop Name: item, Variable Reference: {{dataList}}  (dataList = ["A", "B", "C"])
→ Consumes "A", "B", "C" sequentially, same behavior as array mode
→ If dataList gets new elements during the loop, they are automatically appended to the queue on the next round

Condition Mode

Continues looping while a condition is satisfied; exits when the condition is no longer met. The condition builder works the same way as in Condition Branch — configure left value, operator, and right value. The variables are dynamically resolved and re-evaluated before each iteration.

Note: Condition mode is the easiest to create an infinite loop with. Ensure each iteration changes the variable referenced in the condition so it eventually becomes False; otherwise, the workflow will never exit the loop.

Parameter Reference

Parameter	Type	Default	Description
Loop Name	Text	—	Required. Loop identifier; also used to generate {{loopName.index}} and {{loopName.value}}
Loop Mode	Dropdown	range	range — count; array — array; variable — variable; condition — condition
Start	Number	1	Count mode — start number
End	Number	10	Count mode — end number (exclusive; continues while current < end)
Array	array	—	Array mode — JSON5 format array, e.g., ["A","B","C"]
Variable Reference	Text	—	Variable mode — reference an existing variable. Numbers use count logic; others use array logic
Condition	ConditionBuilder	—	Condition mode — continues looping while condition is satisfied; exits when False

FAQ

Infinite loop won't stop

Symptom: The workflow enters a loop and can't exit.

Cause: In condition mode, the condition is always satisfied — nothing in the loop body changes the referenced variable.

Solution: Ensure the loop body has steps that change the variable referenced in the condition so it eventually becomes False. Count/array/variable modes have explicit iteration endpoints and won't loop infinitely.

Count mode executes fewer times than expected

Symptom: Set Start=1, End=3, expected 3 iterations, but only got 2.

Cause: The end value is exclusive (<, not <=). Continues while start + index < end, so 3 < 3 is False and the loop ends immediately.

Solution: To include the end value, set End to desired value + 1. For example, to execute 3 times (1, 2, 3), set End to 4.