Currency

The Currency type is a union of Token and NativeCurrency. It represents any fungible asset that can be used in Uniswap.

Import

import type { Currency } from '@uniswap/sdk-core-next'

Type Definition

type Currency = NativeCurrency | Token

Usage

Currency is used as a generic type throughout the SDK to handle both native currencies (like ETH) and ERC20 tokens uniformly.

import { Token, Ether, CurrencyAmount, type Currency } from '@uniswap/sdk-core-next'
 
// Both are valid Currency types
const eth: Currency = Ether.onChain(1)
const usdc: Currency = new Token(1, '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', 6, 'USDC')
 
// Create amounts from any currency
const ethAmount = CurrencyAmount.fromRawAmount(eth, '1000000000000000000')
const usdcAmount = CurrencyAmount.fromRawAmount(usdc, '1000000')

Type Guards

You can use the isNative and isToken properties to narrow the type:

function getAddress(currency: Currency): string {
  if (currency.isToken) {
    // TypeScript knows this is a Token
    return currency.address
  }
  // Native currency - return wrapped address
  return currency.wrapped.address
}

Common Properties

All currencies share these properties from BaseCurrency:

Property	Type	Description
`chainId`	`number`	The chain ID where the currency exists
`decimals`	`number`	Number of decimal places
`symbol`	`string \| undefined`	Ticker symbol
`name`	`string \| undefined`	Full name
`isNative`	`boolean`	True for native currencies
`isToken`	`boolean`	True for ERC20 tokens
`wrapped`	`Token`	The wrapped version (e.g., WETH for ETH)

Methods

`equals(other)`

equals(other: Currency): boolean

Returns true if the currencies are equivalent.

const eth = Ether.onChain(1)
const eth2 = Ether.onChain(1)
const usdc = new Token(1, '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', 6)
 
eth.equals(eth2)  // true
eth.equals(usdc)  // false

Working with Currency in Generics

import { CurrencyAmount, type Currency } from '@uniswap/sdk-core-next'
 
// Generic function that works with any currency
function formatAmount<T extends Currency>(amount: CurrencyAmount<T>): string {
  return `${amount.toSignificant(6)} ${amount.currency.symbol}`
}
 
// Works with both native and token amounts
const ethAmount = CurrencyAmount.fromRawAmount(Ether.onChain(1), '1000000000000000000')
const usdcAmount = CurrencyAmount.fromRawAmount(usdc, '1000000')
 
formatAmount(ethAmount)  // "1 ETH"
formatAmount(usdcAmount) // "1 USDC"