initial ws server with lookupToken

blockchain.js

@@ -0,0 +1,21 @@
+import {ethers} from "ethers";
+
+const providers = {} // indexed by chain id
+
+
+export function provider(chainId) {
+    let result = providers[chainId]
+    if( result === undefined ) {
+        const rpc_url = process.env['DEXORDER_RPC_URL_'+chainId]
+        if( rpc_url === undefined ) {
+            console.error('No provider found for chainId',chainId)
+            return null
+        }
+        result = rpc_url.startsWith('ws') ?
+            new ethers.WebSocketProvider(rpc_url, chainId) :
+            new ethers.JsonRpcProvider(rpc_url, chainId)
+        providers[chainId] = result
+    }
+    return result
+}
+