[beta] Optimize signature for fallback function. (#4780)

js/src/abi/util/signature.js

@@ -21,8 +21,9 @@ export function eventSignature (eventName, params) {
   const { strName, name } = parseName(eventName);
   const types = (params || []).map(fromParamType).join(',');
   const id = `${strName}(${types})`;
+  const signature = strName ? keccak_256(id) : '';
 
-  return { id, name, signature: keccak_256(id) };
+  return { id, name, signature };
 }
 
 export function methodSignature (methodName, params) {

js/src/abi/util/signature.spec.js

@@ -46,15 +46,15 @@ describe('abi/util/signature', () => {
       expect(eventSignature(undefined, [])).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d50c3880a2ca1994d5ec287b94b2f4bd832a67d3e41c08177bdd5674fe'
+        signature: ''
       });
     });
 
     it('encodes no-params signature correctly as ()', () => {
       expect(eventSignature(undefined, undefined)).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d50c3880a2ca1994d5ec287b94b2f4bd832a67d3e41c08177bdd5674fe'
+        signature: ''
       });
     });
   });
@@ -96,15 +96,15 @@ describe('abi/util/signature', () => {
       expect(methodSignature(undefined, [])).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d5'
+        signature: ''
       });
     });
 
     it('encodes no-params signature correctly as ()', () => {
       expect(methodSignature(undefined, undefined)).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d5'
+        signature: ''
       });
     });
   });