JavaScript / Web Custom Messages
Define, register, and send product-specific message content.
Content beyond text and images, such as an order card or shared location, can extend MessageContent. Every client must use the same type number and JSON fields for the same content.
1. Define the content
10001 is only an example; maintain a shared registry of type numbers so product messages do not collide.
class OrderMessageContent extends MessageContent {
orderID = ''
title = ''
constructor(orderID = '', title = '') {
super()
this.orderID = orderID
this.title = title
}
get contentType(): number {
return 10001
}
get conversationDigest(): string {
return `[Order] ${this.title}`
}
encodeJSON() {
return {
order_id: this.orderID,
title: this.title,
}
}
decodeJSON(value: Record<string, unknown>) {
this.orderID = typeof value.order_id === 'string' ? value.order_id : ''
this.title = typeof value.title === 'string' ? value.title : ''
}
}Validate types and missing fields while decoding because users can run different application versions.
2. Register before connecting
const ORDER_CONTENT_TYPE = 10001
sdk.register(ORDER_CONTENT_TYPE, () => new OrderMessageContent())Register once in each page context. Unregistered content is decoded as an unknown type.
3. Send and render
await sdk.chatManager.send(
new OrderMessageContent('order-2026-001', 'Coffee beans'),
new Channel('bob', ChannelTypePerson),
)Inspect the runtime type when receiving:
if (message.content instanceof OrderMessageContent) {
showOrder(message.content.orderID, message.content.title)
} else {
showUnsupportedMessage()
}Give new fields defaults, do not reuse old fields for new meanings, and never change a published type number. Field names and numbers must match exactly across iOS, Android, Flutter, and HarmonyOS.