perf: use faster check for $$ prefix

kseamon · IgorMinar · commit cb29632a5802 · 2013-12-17T11:43:57.000-08:00
Use two calls to charAt instead of substr to detect a $$prefix in the shallowCopy functions. This makes shallowCopy 25-50% faster (depending on which browser is used). http://jsperf.com/angular-shallow-copy Closes angular#5457
diff --git a/src/Angular.js b/src/Angular.js
@@ -769,7 +769,7 @@ function shallowCopy(src, dst) {
   for(var key in src) {
     // shallowCopy is only ever called by $compile nodeLinkFn, which has control over src
     // so we don't need to worry about using our custom hasOwnProperty here
-    if (src.hasOwnProperty(key) && key.substr(0, 2) !== '$$') {
+    if (src.hasOwnProperty(key) && key.charAt(0) !== '$' && key.charAt(1) !== '$') {
       dst[key] = src[key];
     }
   }
diff --git a/src/ngResource/resource.js b/src/ngResource/resource.js
@@ -35,7 +35,7 @@ function shallowClearAndCopy(src, dst) {
   });
 
   for (var key in src) {
-    if (src.hasOwnProperty(key) && key.substr(0, 2) !== '$$') {
+    if (src.hasOwnProperty(key) && key.charAt(0) !== '$' && key.charAt(1) !== '$') {
       dst[key] = src[key];
     }
   }

Original file line number	Diff line number	Diff line change
`@@ -769,7 +769,7 @@ function shallowCopy(src, dst) {`
`769`	`769`	`for(var key in src) {`
`770`	`770`	`// shallowCopy is only ever called by $compile nodeLinkFn, which has control over src`
`771`	`771`	`// so we don't need to worry about using our custom hasOwnProperty here`
`772`		`- if (src.hasOwnProperty(key) && key.substr(0, 2) !== '$$') {`
	`772`	`+ if (src.hasOwnProperty(key) && key.charAt(0) !== '$' && key.charAt(1) !== '$') {`
`773`	`773`	`dst[key] = src[key];`
`774`	`774`	`}`
`775`	`775`	`}`
Original file line number	Diff line number	Diff line change
`@@ -35,7 +35,7 @@ function shallowClearAndCopy(src, dst) {`
`35`	`35`	`});`
`36`	`36`
`37`	`37`	`for (var key in src) {`
`38`		`- if (src.hasOwnProperty(key) && key.substr(0, 2) !== '$$') {`
	`38`	`+ if (src.hasOwnProperty(key) && key.charAt(0) !== '$' && key.charAt(1) !== '$') {`
`39`	`39`	`dst[key] = src[key];`
`40`	`40`	`}`
`41`	`41`	`}`