Evaluating Flags

`getFlag(key)`

Returns the data for a specific flag, or undefined if the flag does not exist.


const flag = canary.getFlag('new-checkout')
// FlagData | undefined

Safe check with nullish coalescing


const isEnabled = canary.getFlag('new-checkout')?.enabled ?? false

The SDK does not expose an isEnabled() method. Always use the pattern getFlag(key)?.enabled ?? false.

`getFlags()`

Returns all flags for the environment as an array.


const flags = canary.getFlags()
// FlagData[]
 
for (const flag of flags) {
  console.log(flag.key, flag.enabled)
}

Examples by flag type

Boolean flag


const maintenance = canary.getFlag('maintenance-mode')
 
if (maintenance?.enabled) {
  return <MaintenancePage />
}

Rollout flag


const newDashboard = canary.getFlag('new-dashboard')
 
// flag.enabled is true or false based on userId and percentage
if (newDashboard?.enabled) {
  return <NewDashboard />
}
 
// To see the configured percentage:
if (newDashboard?.type === 'rollout') {
  console.log(`${newDashboard.percent}% of users will see this feature`)
}

Before `init()`

If you call getFlag() before await init(), the flag will return undefined (the local cache is still empty).


const client = new CanaryGate('cg_key')
// Do not do this:
client.getFlag('feature') // undefined!
 
// Do this instead:
await client.init()
client.getFlag('feature') // FlagData | undefined ✓

Flags that do not exist

If the flag does not exist in the environment, getFlag() returns undefined. Always use ?? false as a fallback to avoid breaking the application flow:


// If 'new-feature' does not exist in the environment, isEnabled will be false
const isEnabled = canary.getFlag('new-feature')?.enabled ?? false

getFlag(key)