extract tapleaf identification function

Author: philippem

client/src/lib/elements.js

@@ -40,10 +40,14 @@ const getControlBlock = witness => {
     return witness[witness.length - 1]
 }
 
+export const isSimplicityTapleafVersion = (controlBlock) => {
+    return controlBlock && (controlBlock.startsWith('be') || controlBlock.startsWith('bf'))
+}
+
 // Check if a vin is a P2TR Simplicity spend
 // A P2TR Simplicity spend has:
 // - 4 witness elements (or 5 with optional annex)
-// - Control block starts with 'be' or 'bf' (leaf version for Simplicity)
+// - is a simplicity Tapleaf
 export const isSimplicitySpend = (vin) => {
     if (!process.env.IS_ELEMENTS || !vin.witness) return false
 
@@ -54,7 +58,7 @@ export const isSimplicitySpend = (vin) => {
     if (witnessLen !== 4 && !(witnessLen === 5 && hasAnnexBlock)) return false
 
     const controlBlock = getControlBlock(vin.witness)
-    return controlBlock && (controlBlock.startsWith('be') || controlBlock.startsWith('bf'))
+    return isSimplicityTapleafVersion(controlBlock)
 }
 
 // Extract Simplicity witness components from a vin