From 83b2fa9371f94510a6e13194de86060f3f6b4ef2 Mon Sep 17 00:00:00 2001
From: Ardis Lu <ardisglu@gmail.com>
Date: Wed, 22 Nov 2023 22:11:10 -0800
Subject: [PATCH] Implement ERC-55 mixed-case checksum address

---
 index.html | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/index.html b/index.html
index 218efd9..527e34e 100644
--- a/index.html
+++ b/index.html
@@ -431,6 +431,25 @@
       return addresses;
     }
 
+    // ERC-55: https://ercs.ethereum.org/ERCS/erc-55
+    function toChecksumAddress(address) {
+      address = address.toLowerCase().replace('0x', '');
+      // Hash the address (treat it as UTF-8) and return as a hex string
+      const hash = [...keccak256(address)].map(v => v.toString(16).padStart(2, '0')).join('');
+      let ret = '0x';
+
+      for (let i = 0; i < 40; i++) {
+        if (parseInt(hash[i], 16) >= 8) {
+          ret += address[i].toUpperCase();
+        }
+        else {
+          ret += address[i];
+        }
+      }
+
+      return ret;
+    }
+
     document.querySelector('form').addEventListener('submit', async event => {
       event.preventDefault();
 
@@ -472,7 +491,7 @@
 
         ens.textContent = name;
         const response = multicallResponse[name];
-        address.textContent = response;
+        address.textContent = toChecksumAddress(response);
       }
 
       spinner.style.setProperty('display', 'none');
-- 
2.47.3