MessagePort: close() method
  The close() method of the MessagePort
  interface disconnects the port, so it is no longer active. This stops the flow of
  messages to that port.
Note: This feature is available in Web Workers
Syntax
js
close()
Parameters
None.
Return value
None (undefined).
Examples
  In the following code block, you can see a handleMessage handler function,
  run when a message is sent back to this document using
  EventTarget.addEventListener.
js
channel.port1.addEventListener("message", handleMessage, false);
function handleMessage(e) {
  para.innerHTML = e.data;
  textInput.value = "";
}
channel.port1.start();
You could stop messages being sent at any time using
js
channel.port1.close();
Specifications
| Specification | 
|---|
| HTML Standard  # dom-messageport-close-dev  | 
Browser compatibility
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