Merge pull request #7 from sgrowe/memoisation

Add memoisation of functions

Author: developit

README.md

@@ -2,7 +2,7 @@
 
 > Create an Event handler function that sets a given state property. Works with [preact] and [react].
 
--   **Tiny:** less than **300 bytes** of [ES3](https://unpkg.com/linkstate) gzipped
+-   **Tiny:** less than **350 bytes** of [ES3](https://unpkg.com/linkstate) gzipped
 -   **Familiar:** it's just a function that does what you would have done manually
 -   **Standalone:** one function, no dependencies, works everywhere
 

src/index.js

@@ -8,7 +8,9 @@ import delve from 'dlv';
  */
 export default function linkState(component, key, eventPath) {
 	let path = key.split('.');
-	return function(e) {
+	const cache = component._linkedStates || (component._linkedStates = {});
+
+	return cache[`${key}\n${eventPath}`] || (cache[`${key}\n${eventPath}`] = function(e) {
 		let t = e && e.target || this,
 			state = {},
 			obj = state,
@@ -19,5 +21,5 @@ export default function linkState(component, key, eventPath) {
 		}
 		obj[path[i]] = v;
 		component.setState(state);
-	};
+	});
 }

test/index.js

@@ -110,4 +110,13 @@ describe('linkstate', () => {
 			expect(component.setState).to.have.been.calledWith({'testStateKey': 'nestedPathValueFromEvent'});
 		});
 	});
+
+	describe('linkState memoisation', () => {
+		it('should return the same function when called with the same inputs', () => {
+			linkFunction = linkState(component, 'nested.state.key');
+			const linkFunctionB = linkState(component, 'nested.state.key');
+
+			expect(linkFunction).to.equal(linkFunctionB);
+		});
+	});
 });