From 33c93b5ded245765ddefcf796b733ed5ce13ab3d Mon Sep 17 00:00:00 2001
From: Zach Pomerantz <zzmp@uniswap.org>
Date: Mon, 18 Sep 2023 13:08:37 -0700
Subject: [PATCH] fix: spurious Swap re-renders (#7333)

---
 src/components/Tokens/TokenDetails/index.tsx |  6 ++---
 src/pages/Swap/index.tsx                     | 23 +++++++++++++-------
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/components/Tokens/TokenDetails/index.tsx b/src/components/Tokens/TokenDetails/index.tsx
index b4b798094c..ac4eb0e161 100644
--- a/src/components/Tokens/TokenDetails/index.tsx
+++ b/src/components/Tokens/TokenDetails/index.tsx
@@ -248,10 +248,8 @@ export default function TokenDetails({
           <div style={{ pointerEvents: isBlockedToken ? 'none' : 'auto' }}>
             <Swap
               chainId={pageChainId}
-              prefilledState={{
-                [Field.INPUT]: { currencyId: inputTokenAddress },
-                [Field.OUTPUT]: { currencyId: address === NATIVE_CHAIN_ID ? 'ETH' : address },
-              }}
+              initialInputCurrencyId={inputTokenAddress}
+              initialOutputCurrencyId={address === NATIVE_CHAIN_ID ? 'ETH' : address}
               onCurrencyChange={handleCurrencyChange}
               disableTokenInputs={pageChainId !== connectedChainId}
             />
diff --git a/src/pages/Swap/index.tsx b/src/pages/Swap/index.tsx
index d0716b211e..bda2feb3c4 100644
--- a/src/pages/Swap/index.tsx
+++ b/src/pages/Swap/index.tsx
@@ -150,10 +150,8 @@ export default function SwapPage({ className }: { className?: string }) {
         <Swap
           className={className}
           chainId={supportedChainId ?? ChainId.MAINNET}
-          prefilledState={{
-            [Field.INPUT]: { currencyId: loadedUrlParams?.[Field.INPUT]?.currencyId },
-            [Field.OUTPUT]: { currencyId: loadedUrlParams?.[Field.OUTPUT]?.currencyId },
-          }}
+          initialInputCurrencyId={loadedUrlParams?.[Field.INPUT]?.currencyId}
+          initialOutputCurrencyId={loadedUrlParams?.[Field.OUTPUT]?.currencyId}
           disableTokenInputs={supportedChainId === undefined}
         />
         <NetworkAlert />
@@ -172,13 +170,15 @@ export default function SwapPage({ className }: { className?: string }) {
  */
 export function Swap({
   className,
-  prefilledState = {},
+  initialInputCurrencyId,
+  initialOutputCurrencyId,
   chainId,
   onCurrencyChange,
   disableTokenInputs = false,
 }: {
   className?: string
-  prefilledState?: Partial<SwapState>
+  initialInputCurrencyId?: string | null
+  initialOutputCurrencyId?: string | null
   chainId?: ChainId
   onCurrencyChange?: (selected: Pick<SwapState, Field.INPUT | Field.OUTPUT>) => void
   disableTokenInputs?: boolean
@@ -187,8 +187,8 @@ export function Swap({
   const trace = useTrace()
 
   // token warning stuff
-  const prefilledInputCurrency = useCurrency(prefilledState?.[Field.INPUT]?.currencyId)
-  const prefilledOutputCurrency = useCurrency(prefilledState?.[Field.OUTPUT]?.currencyId)
+  const prefilledInputCurrency = useCurrency(initialInputCurrencyId)
+  const prefilledOutputCurrency = useCurrency(initialOutputCurrencyId)
 
   const [loadedInputCurrency, setLoadedInputCurrency] = useState(prefilledInputCurrency)
   const [loadedOutputCurrency, setLoadedOutputCurrency] = useState(prefilledOutputCurrency)
@@ -236,6 +236,13 @@ export function Swap({
   const toggleWalletDrawer = useToggleAccountDrawer()
 
   // swap state
+  const prefilledState = useMemo(
+    () => ({
+      [Field.INPUT]: { currencyId: initialInputCurrencyId },
+      [Field.OUTPUT]: { currencyId: initialOutputCurrencyId },
+    }),
+    [initialInputCurrencyId, initialOutputCurrencyId]
+  )
   const [state, dispatch] = useReducer(swapReducer, { ...initialSwapState, ...prefilledState })
   const { typedValue, recipient, independentField } = state