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Overview

Communication between CFS/Pages and third-party POS systems (Clover, PAX) is implemented via JavaScript iframe events using window.postMessage() Event Model: 
export enum IframeMessageTypes {
  buttonClick = "buttonClick",
  inputFocus = "inputFocus",
  inputBlur = "inputBlur",
  formSubmitted = "formSubmitted",
  userActivity = "userActivity",
  setWindowClass = "setWindowClass",
  scanCompleted = "scanCompleted",
  scanCancelled = "scanCancelled",
  init = "init",
}

interface IframeMessageData<T> {
  type: IframeMessageTypes;
  data: T;
}
Events are exchanged with: 
window.postMessage(params, "*");

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Output Events (Sent by CFS → External System)

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init

Description
Triggered on CFS application initialization. Post Message Example 
window.postMessage(
  {
    type: "init",
    data: {
      projectName: "cfs",
    },
  },
  "*"
);
Parameters
FieldDescription
projectNameStatic string “cfs” – identifies the source project

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buttonClick

Description
Emitted when a button is clicked in CFS. Used to request external scanner usage (e.g., Check-In UI). Post Message Example 
window.postMessage(
  {
    type: "buttonClick",
    data: {
      targetId: "scan",
      buttonId: "scan",
    },
  },
  "*"
);
Parameters
FieldDescription
targetIdHTML element ID of the clicked button (e.g., “scan”)
buttonIdDeprecated. Legacy support only (use targetId instead).

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inputFocus

Description
Emitted when an input field in CFS gains focus. Can notify the external POS to prepare for login/check-in actions. Post Message Example 
window.postMessage(
  {
    type: "inputFocus",
    data: {
      targetId: "search",
      inputId: "search",
    },
  },
  "*"
);
Parameters
FieldDescription
targetIdHTML element ID of the input field (e.g., “search”)
inputIdDeprecated. Legacy support only (use targetId instead).

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inputBlur

Description
Emitted when an input field in CFS loses focus. Post Message Example 
window.postMessage(
  {
    type: "inputBlur",
    data: {
      targetId: "search",
      inputId: "search",
    },
  },
  "*"
);
Parameters
FieldDescription
targetIdHTML element ID of the input field (e.g., “search”)
inputIdDeprecated. Legacy support only (use targetId instead).

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Input Events (Received by CFS ← External System)

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formSubmitted

Description
Instructs CFS to close the current iframe window (e.g., after external form submit in CFS Template iframe). Parameters
No additional parameters.

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userActivity

Description
Used to prolong user activity inside the iframe (prevent “Are you still here?” prompts). Parameters
No additional parameters.

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setWindowClass

Description
Previously used to set CSS class on iframe window.
Currently considered deprecated.

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scanCompleted

Description
Delivers the result of an external scan (barcode, QR, username, email). Used for login/check-in. Example Payload 
{
  type: "scanCompleted",
  data: "user@example.com"
}
Parameters
FieldDescription
dataString value representing scan result (username, code, email)

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scanCancelled

Description
Indicates cancellation of a scan request. Typically results in:
  • Showing a toast message to the user.
  • Resending cancellation notice to the external system.
Parameters
No additional parameters.