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Communication between an iframe and its parent window

Written byPhuoc Nguyen
08 Mar, 2020
Level 2 — Intermediate

Send data from an iframe to its parent window

// Called from the iframe
window.parent.postMessage(message, '*');
Where `message` is a string. If you want to send multiple data, you can encode in JSON:
// Called from the iframe
const message = JSON.stringify({
message: 'Hello from iframe',
date: Date.now(),
window.parent.postMessage(message, '*');

Send data from a page to its child iframe

// Called from the page
frameEle.contentWindow.postMessage(message, '*');
Where `frameEle` represents the iframe element.

Receive the sent data

In the iframe or main page, you can listen on the `message` event to receive the sent data:
window.addEventListener('message', function (e) {
// Get the sent data
const data = e.data;

// If you encode the message in JSON before sending them,
// then decode here
// const decoded = JSON.parse(data);


If you send or receive message from different iframes, you can include a parameter to indicate where the message comes from.
// From a child iframe
const message = JSON.stringify({
channel: 'FROM_FRAME_A',
window.parent.postMessage(message, '*');
Then in the main page, you can distinguish the messages by looking at the parameter:
window.addEventListener('message', function (e) {
const data = JSON.parse(e.data);
// Where does the message come from
const channel = data.channel;
Here is an example demonstrates how to send a simple message between a page and a child iframe:


See also

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Phước Nguyễn