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passToClient

Most pageContext properties are available only on the server-side, but you can use passToClient to make properties available on the client-side.

// /pages/+config.js
// Environment: config
 
export default {
  passToClient: [
    // pageContext.someData
    'someData',
    // pageContext.user.id
    'user.id', // Nested
    // pageContext.user.info.avatar.url
    'user.info.avatar.url', // Deeply nested
  ]
}
// /pages/+onHydrationEnd.js
// Environment: client
 
export { onHydrationEnd }
 
async function onHydrationEnd(pageContext) {
  // pageContext.user.id is available here thanks to passToClient
  console.log(pageContext.user.id)
 
  // ...
}

Some values, such as pageContext.data, are already passed to the client-side by default.

The nesting delimiter . can be escaped.

It also applies to globalContext.

Default

When using Client Routing, the following are also available on the client-side by default:

  • pageContext.Page
  • pageContext.data
  • pageContext.config
  • pageContext.isHydration
  • pageContext.isBackwardNavigation
  • pageContext.routeParams
  • pageContext.urlOriginal
  • pageContext.urlPathname
  • pageContext.urlParsed

When using Server Routing, the following are also available on the client-side by default:

  • pageContext.Page
  • pageContext.data
  • pageContext.config
  • pageContext.routeParams

Serialization

Serialization is done with @brillout/json-serializer.

User-defined classes are lost during serialization:

class MyClass {
  prop = 42
}
 
// On the server-side:
const obj = new MyClass()
console.log(obj) // MyClass { prop: 42 }
console.log(obj instanceof MyClass) // true
 
// On the browser-side, after `obj` was (de)serialized:
console.log(obj) // { prop: 42 }
console.log(obj instanceof MyClass) // false

See GitHub > brillout/json-serializer > #3 Support user-defined classes.

Escape

In the (unlikely) event you need to pass properties that include . in their name:

// /pages/+config.js
// Environment: config
 
export default {
  passToClient: [
    // pageContext['some-weird.prop-name']
    'some-weird\\.prop-name',
    // pageContext['some-weird\\.prop-name']
    'some-weird\\\\.prop-name',
    // pageContext['some-weird\\\\.prop-name']
    'some-weird\\\\\\.prop-name'
  ]
}

See also