ComfyUI_frontend/src/extensions/core/dynamicPrompts.ts

// @ts-strict-ignore
import { app } from '../../scripts/app'

// Allows for simple dynamic prompt replacement
// Inputs in the format {a|b} will have a random value of a or b chosen when the prompt is queued.

/*
 * Strips C-style line and block comments from a string
 */
function stripComments(str) {
  return str.replace(/\/\*[\s\S]*?\*\/|\/\/.*/g, '')
}

app.registerExtension({
  name: 'Comfy.DynamicPrompts',
  nodeCreated(node) {
    if (node.widgets) {
      // Locate dynamic prompt text widgets
      // Include any widgets with dynamicPrompts set to true, and customtext
      const widgets = node.widgets.filter((n) => n.dynamicPrompts)
      for (const widget of widgets) {
        // Override the serialization of the value to resolve dynamic prompts for all widgets supporting it in this node
        widget.serializeValue = (workflowNode, widgetIndex) => {
          let prompt = stripComments(widget.value)
          while (
            prompt.replace('\\{', '').includes('{') &&
            prompt.replace('\\}', '').includes('}')
          ) {
            const startIndex = prompt.replace('\\{', '00').indexOf('{')
            const endIndex = prompt.replace('\\}', '00').indexOf('}')

            const optionsString = prompt.substring(startIndex + 1, endIndex)
            const options = optionsString.split('|')

            const randomIndex = Math.floor(Math.random() * options.length)
            const randomOption = options[randomIndex]

            prompt =
              prompt.substring(0, startIndex) +
              randomOption +
              prompt.substring(endIndex + 1)
          }

          // Overwrite the value in the serialized workflow pnginfo
          if (workflowNode?.widgets_values)
            workflowNode.widgets_values[widgetIndex] = prompt

          return prompt
        }
      }
    }
  }
})