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Overview

TransactionIndex is a branded number type representing a transaction’s position within a block. Indices start at 0 for the first transaction in a block. 
import * as TransactionIndex from '@tevm/primitives/TransactionIndex'

const index = TransactionIndex.from(5)

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Type Definition

type TransactionIndexType = number & {
  readonly [brand]: "TransactionIndex";
}

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Creating TransactionIndexes

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from

Create from number or bigint. 
// From number
const idx1 = TransactionIndex.from(5)

// From bigint
const idx2 = TransactionIndex.from(5n)

// First transaction in block
const first = TransactionIndex.from(0)
Validation: Must be non-negative integer.

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Converting TransactionIndexes

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toNumber

Convert to number (zero-cost). 
const num = TransactionIndex.toNumber(index)
// 5

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Comparing TransactionIndexes

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equals

Check equality. 
const a = TransactionIndex.from(5)
const b = TransactionIndex.from(5)

if (TransactionIndex.equals(a, b)) {
  console.log('Indexes are equal')
}

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Usage in Receipts

TransactionIndex appears in transaction receipts to indicate position within a block: 
import * as Receipt from '@tevm/primitives/Receipt'

const receipt = Receipt.from({
  transactionIndex: TransactionIndex.from(3),
  // ... other fields
})

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Errors

InvalidTransactionIndexError: Invalid value (negative, non-integer, wrong type).

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See Also