# TxEnvelopeLegacy.assert

Asserts a [`TxEnvelopeLegacy.TxEnvelopeLegacy`](/api/TxEnvelopeLegacy/types#txenvelopelegacy) is valid.

## Imports

:::code-group
```ts [Named]
import { TxEnvelopeLegacy } from 'ox'
```

```ts [Entrypoint]
import * as TxEnvelopeLegacy from 'ox/TxEnvelopeLegacy'
```
:::

## Examples

```ts twoslash
import { TxEnvelopeLegacy, Value } from 'ox'

TxEnvelopeLegacy.assert({
  gasPrice: 2n ** 256n - 1n + 1n,
  chainId: 1,
  to: '0x0000000000000000000000000000000000000000',
  value: Value.fromEther('1')
})
// @error: GasPriceTooHighError:
// @error: The gas price (`gasPrice` = 115792089237316195423570985008687907853269984665640564039457584007913 gwei) cannot be
// @error: higher than the maximum allowed value (2^256-1).
```

## Definition

```ts
function assert(
  envelope: PartialBy<TxEnvelopeLegacy, 'type'>,
): void
```

**Source:** [src/core/TxEnvelopeLegacy.ts](https://github.com/wevm/ox/blob/main/src/core/TxEnvelopeLegacy.ts#L671)

## Parameters

### envelope

* **Type:** `PartialBy<TxEnvelopeLegacy, 'type'>`

The transaction envelope to assert.

## Return Type

`void`