Get the last matching element

Find and use the last matching index for a given selector in Maestro

In Maestro you can choose to target the n^th element matching a selector using indexes, e.g.

- tapOn:
    text: Add to Basket
    index: 2   # 3rd item, indexes start at 0

What if you want the last item on the screen, but don't know how many there are? That's harder, and requires an algorithmic approach.

This helper comes courtesy of Ben Sussman from Pomelo Care, probably best used as a subflow, loops through visible elements for a given selector, and returns the index of the last matching element.

# A reusable helper to find the last element matching a given selector.
# Usage:
#   - runFlow:
#       file: utils/findLastElement.yml
#       env:
#         SELECTOR_TYPE: "id"          # Supported: "id", "text"
#         SELECTOR_VALUE: "my_button"  # The actual selector value
#
# After running, the last element index will be available as ${output.lastElementIndex}
#
# Example usage:
#
# - runFlow:
#     file: ../utils/findLastElement.yml
#     env:
#       SELECTOR_TYPE: "text"
#       SELECTOR_VALUE: "Add to Basket"
# - tapOn:
#   text: "Add to Basket"
#   index: ${output.lastElementIndex}

# Initialize variables (always reset for fresh execution)
- evalScript: ${output.lastElementIndex = -1}
- evalScript: ${output._findLastElement_complete = false}


# Validate SELECTOR_TYPE
- runFlow:
    when:
      true: ${SELECTOR_TYPE != "id" && SELECTOR_TYPE != "text"}
    commands:
      - evalScript: |
          throw new Error("Invalid SELECTOR_TYPE: " + SELECTOR_TYPE + ". Must be 'id' or 'text'");

# Find the last element by iterating through indices
- repeat:
    while:
      true: ${!output._findLastElement_complete}
    commands:
      # Check if element exists at current index (id selector)
      - runFlow:
          when:
            true: ${SELECTOR_TYPE == "id"}
          commands:
            - runFlow:
                when:
                  visible:
                    id: "${SELECTOR_VALUE}"
                    index: ${output.lastElementIndex + 1}
                commands:
                  # Element found, update index and continue
                  - evalScript: ${output.lastElementIndex = output.lastElementIndex + 1}
            - runFlow:
                when:
                  notVisible:
                    id: "${SELECTOR_VALUE}"
                    index: ${output.lastElementIndex + 1}
                commands:
                  # Element not found, we're done
                  - evalScript: ${output._findLastElement_complete = true}

      # Check if element exists at current index (text selector)
      - runFlow:
          when:
            true: ${SELECTOR_TYPE == "text"}
          commands:
            - runFlow:
                when:
                  visible:
                    text: "${SELECTOR_VALUE}"
                    index: ${output.lastElementIndex + 1}
                commands:
                  # Element found, update index and continue
                  - evalScript: ${output.lastElementIndex = output.lastElementIndex + 1}
            - runFlow:
                when:
                  notVisible:
                    text: "${SELECTOR_VALUE}"
                    index: ${output.lastElementIndex + 1}
                commands:
                  # Element not found, we're done
                  - evalScript: ${output._findLastElement_complete = true}

# Validate that at least one element was found
- runFlow:
    when:
      true: ${output.lastElementIndex == -1}
    commands:
      - evalScript: |
          throw new Error("No elements found matching selector: " + SELECTOR_TYPE + '="' + SELECTOR_VALUE + '"');>