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

@@ -46,7 +46,7 @@ describe('abi/util/signature', () => {
       expect(eventSignature(undefined, [])).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d50c3880a2ca1994d5ec287b94b2f4bd832a67d3e41c08177bdd5674fe'
+        signature: ''
       });
     });
 
@@ -54,7 +54,7 @@ describe('abi/util/signature', () => {
       expect(eventSignature(undefined, undefined)).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d50c3880a2ca1994d5ec287b94b2f4bd832a67d3e41c08177bdd5674fe'
+        signature: ''
       });
     });
   });
@@ -96,7 +96,7 @@ describe('abi/util/signature', () => {
       expect(methodSignature(undefined, [])).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d5'
+        signature: ''
       });
     });
 
@@ -104,7 +104,7 @@ describe('abi/util/signature', () => {
       expect(methodSignature(undefined, undefined)).to.deep.equal({
         id: '()',
         name: undefined,
-        signature: '861731d5'
+        signature: ''
       });
     });
   });

js/src/api/util/encode.js

@@ -34,7 +34,5 @@ export function abiEncode (methodName, inputTypes, data) {
     })
   }, data);
 
-  return methodName === null
+  return result;
-    ? `0x${result.substr(10)}`
-    : result;
 }