> ## Documentation Index
> Fetch the complete documentation index at: https://elastly.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# TypeScript SDK

> Price lines with a hard deadline and a fallback, verify webhooks, and sync a connector, from Node.js.

The `@elastly/sdk` package is the supported way to call Elastly from Node.js. It is not a thin wrapper
around HTTP. It solves the problems every integration hits: a price call that must never break your
quote screen, typed errors you can branch on, webhooks you can trust, and a connector that pages,
checkpoints, retries, and reports without you writing any of it.

```bash theme={null}
npm install @elastly/sdk
```

Node 20.3 or later. Ships ESM and CommonJS, fully typed. Its only dependency is
`@elastly/api-contract`, the same schema package our servers validate against, so the types in your
editor cannot drift from the API.

## Keys and scopes

Create API keys under [Settings → API keys](https://app.elastly.io/settings). Scopes are separate on
purpose: a serving key can never write your catalog, and a connector key can never read prices.

| Scope         | Used for               | SDK surface                                               |
| ------------- | ---------------------- | --------------------------------------------------------- |
| **ERP**       | Price serving          | `elastly.prices`                                          |
| **Connector** | Ingest and write-backs | `elastly.ingest`, `elastly.writebacks`, `defineConnector` |

```ts theme={null}
import { Elastly } from "@elastly/sdk"

const elastly = new Elastly({ apiKey: process.env.ELASTLY_API_KEY })
```

## The one thing to get right: the decision id

Every priced line comes back with a `pricingDecisionId`. **Store it in your own system, on the quote
line it priced.** When that quote later closes and you send it back to Elastly, the id ties what
Elastly recommended to what your rep actually charged. That difference is what the model learns from.

Skip it and everything still looks like it works: prices serve, quotes ingest, dashboards fill. But the
model learns nothing from your quotes, and nothing tells you. So wire it first:

```ts theme={null}
const result = await elastly.prices.get(line, { failOpen })

if (result.source === "elastly") {
  await erp.updateQuoteLine(quoteLineId, {
    elastlyPriceCents: result.priceCents,
    elastlyDecisionId: result.pricingDecisionId,
  })
}
```

## Price a line, with a fallback

A price call usually runs inside a rep's quote screen or a checkout render. If Elastly is slow or down,
your system must keep working. The SDK makes that a policy you declare, not code you write:

```ts theme={null}
import { staticFallback } from "@elastly/sdk"

const failOpen = staticFallback((line) => ({ priceCents: erp.listPrice(line.productSku) }), {
  deadlineMs: 800,
})

const result = await elastly.prices.get(
  { customerExternalId: "cust-1042", productSku: "VLV-200", quantity: 25 },
  { failOpen },
)

if (result.source === "elastly") {
  render(result.priceCents, result.reasonSummary, result.explanation)
} else if (result.source === "fallback") {
  render(result.priceCents) // result.cause.reason tells you why
}
```

Under this policy a timeout, a 5xx, a rate limit, a malformed body, or a network failure never throws.
The SDK retries where it can, then calls your fallback and returns `{ source: "fallback" }` with the
cause attached. If your fallback returns `null`, you get `{ source: "unavailable" }`, an explicit typed
no-answer.

Three things throw on purpose. A `4xx` that means your request is wrong (`invalid_request`,
`feature_not_enabled`) throws a typed error, because a bug in your integration is not an outage to paper
over. An exception inside your own fallback surfaces. And the `throwOnFailure()` policy throws on
everything, for batch jobs where a wrong price is worse than no price:

```ts theme={null}
import { throwOnFailure } from "@elastly/sdk"

const results = await elastly.prices.getMany(lines, { failOpen: throwOnFailure() })
```

`getMany` prices up to 100 lines in one HTTP call. One unknown SKU fails that line alone, never the
whole batch.

## Typed errors

Every error is a typed class carrying the stable error code and the `x-elastly-request-id` of the call,
so support can find the exact request. Branch on the class or on `error.code`:

```ts theme={null}
import { ApiError, RateLimitError, UnknownProductError } from "@elastly/sdk"

try {
  await elastly.prices.get(line, { failOpen: throwOnFailure() })
} catch (error) {
  if (error instanceof RateLimitError) console.log(error.retryAfterMs)
  else if (error instanceof UnknownProductError) console.log(error.requestId)
  else if (error instanceof ApiError) console.log(error.code, error.status)
}
```

There is one class per API error code (`UnknownProductError`, `NoCostBasisError`,
`MonthlyVolumeExceededError`, and the rest), all extending `ApiError`, which extends `ElastlyError`.
Catch the base class to handle anything.

## Verify a webhook

```ts theme={null}
const event = elastly.webhooks.verify(rawBody, request.headers["elastly-signature"], secret)

if (event.event === "sync.completed") {
  console.log(event.data.connector, event.data.totals)
}
```

`verify` checks the signature in constant time, rejects anything older than five minutes, and returns a
typed event. It throws `SignatureVerificationError` on a bad signature, a replay, or a malformed body.
The four event types are `sync.completed`, `recommendation.created`, `price.written_back`, and
`test.ping`.

## What the SDK handles for you

* **Idempotency.** Every mutating call carries a key that stays stable across retries, so a retried
  price call can never double-count against your plan.
* **Retries.** Failed calls back off with full jitter and honor `Retry-After` and `RateLimit-Reset`.
* **A circuit breaker.** After repeated failures it stops hammering Elastly and goes straight to your
  fallback, then probes once to recover.
* **Fail-open telemetry.** Every call that falls open reports itself to Elastly (fire and forget, never
  on your latency path), so an outage that hit your quote screen shows up in your dashboard instead of
  staying invisible.

## Build a connector

To push your own ERP or storefront into Elastly, the SDK ships a connector runtime: implement a few
functions that read your data, and `defineConnector` runs the whole sync, with paging, checkpoints,
retries, and write-back leases handled for you.

<Card title="Build a connector" icon="wrench" href="/sdks/build-a-connector">
  Feed your data in, apply approved prices back, in TypeScript or any other language.
</Card>

## Versioning

The SDK's major version is bound to the API version in the URL. Every `0.x` and `1.x` release of
`@elastly/sdk` talks to `/api/v1`. A major release of the SDK is the only thing that ever changes which
API version an installed integration calls, so an upgrade within a major is always safe.

The source is published to [npm](https://www.npmjs.com/package/@elastly/sdk).