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Overview

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

const index = LogIndex.from(2)

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Type Definition

type LogIndexType = number & {
  readonly [brand]: "LogIndex";
}

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Creating LogIndexes

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from

Create from number or bigint. 
// From number
const idx1 = LogIndex.from(2)

// From bigint
const idx2 = LogIndex.from(2n)

// First log
const first = LogIndex.from(0)
Validation: Must be non-negative integer.

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Converting LogIndexes

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toNumber

Convert to number (zero-cost). 
const num = LogIndex.toNumber(index)
// 2

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Comparing LogIndexes

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equals

Check equality. 
const a = LogIndex.from(2)
const b = LogIndex.from(2)

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

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Usage in Event Logs

LogIndex appears in event logs to indicate position within a receipt: 
import * as EventLog from '@tevm/primitives/EventLog'

const log = {
  logIndex: LogIndex.from(2),
  address: contractAddress,
  topics: [eventSignature],
  data: eventData
}

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Errors

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

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See Also