perf(Scope): change Scope#id to be a simple number

In apps that create lots of scopes (apps with large tables) the uid generation
shows up in the profiler and adds a few milliseconds. Using simple counter
doesn't have this overhead.

I think the initial fear of overflowing and thus using string alphanum sequence
is unjustified because even if an app was to create lots of scopes non-stop,
you could create about 28.6 million scopes per seconds for 10 years before
you would reach a number that can't be accurately represented in JS

BREAKING CHANGE: Scope#$id is now of time number rather than string. Since the
id is primarily being used for debugging purposes this change should not affect
anyone.

src/Angular.js

@@ -167,7 +167,7 @@ var /** holds major version number for IE or NaN for real browsers */
     angular           = window.angular || (window.angular = {}),
     angularModule,
     nodeName_,
-    uid               = ['0', '0', '0'];
+    uid               = 0;
 
 /**
  * IE 11 changed the format of the UserAgent string.
@@ -285,33 +285,17 @@ function reverseParams(iteratorFn) {
 }
 
 /**
- * A consistent way of creating unique IDs in angular. The ID is a sequence of alpha numeric
- * characters such as '012ABC'. The reason why we are not using simply a number counter is that
- * the number string gets longer over time, and it can also overflow, where as the nextId
- * will grow much slower, it is a string, and it will never overflow.
+ * A consistent way of creating unique IDs in angular.
  *
- * @returns {string} an unique alpha-numeric string
+ * Using simple numbers allows us to generate 28.6 million unique ids per second for 10 years before
+ * we hit number precision issues in JavaScript.
+ *
+ * Math.pow(2,53) / 60 / 60 / 24 / 365 / 10 = 28.6M
+ *
+ * @returns {number} an unique alpha-numeric string
  */
 function nextUid() {
-  var index = uid.length;
-  var digit;
-
-  while(index) {
-    index--;
-    digit = uid[index].charCodeAt(0);
-    if (digit == 57 /*'9'*/) {
-      uid[index] = 'A';
-      return uid.join('');
-    }
-    if (digit == 90  /*'Z'*/) {
-      uid[index] = '0';
-    } else {
-      uid[index] = String.fromCharCode(digit + 1);
-      return uid.join('');
-    }
-  }
-  uid.unshift('0');
-  return uid.join('');
+  return ++uid;
 }
 
 

test/AngularSpec.js

@@ -958,7 +958,7 @@ describe('angular', function() {
 
       while(count--) {
         var current = nextUid();
-        expect(current.match(/[\d\w]+/)).toBeTruthy();
+        expect(typeof current).toBe('number');
         expect(seen[current]).toBeFalsy();
         seen[current] = true;
       }

test/helpers/testabilityPatch.js

@@ -24,7 +24,7 @@ beforeEach(function() {
     }
 
     // This resets global id counter;
-    uid = ['0', '0', '0'];
+    uid = 0;
 
     // reset to jQuery or default to us.
     bindJQuery();

test/ng/compileSpec.js

@@ -1885,15 +1885,15 @@ describe('$compile', function() {
 
         it('should allow creation of new scopes', inject(function($rootScope, $compile, log) {
           element = $compile('<div><span scope><a log></a></span></div>')($rootScope);
-          expect(log).toEqual('002; log-002-001; LOG');
+          expect(log).toEqual('2; log-2-1; LOG');
           expect(element.find('span').hasClass('ng-scope')).toBe(true);
         }));
 
 
         it('should allow creation of new isolated scopes for directives', inject(
             function($rootScope, $compile, log) {
           element = $compile('<div><span iscope><a log></a></span></div>')($rootScope);
-          expect(log).toEqual('log-001-no-parent; LOG; 002');
+          expect(log).toEqual('log-1-no-parent; LOG; 2');
           $rootScope.name = 'abc';
           expect(iscope.$parent).toBe($rootScope);
           expect(iscope.name).toBeUndefined();
@@ -1905,11 +1905,11 @@ describe('$compile', function() {
           $httpBackend.expect('GET', 'tscope.html').respond('<a log>{{name}}; scopeId: {{$id}}</a>');
           element = $compile('<div><span tscope></span></div>')($rootScope);
           $httpBackend.flush();
-          expect(log).toEqual('log-002-001; LOG; 002');
+          expect(log).toEqual('log-2-1; LOG; 2');
           $rootScope.name = 'Jozo';
           $rootScope.$apply();
-          expect(element.text()).toBe('Jozo; scopeId: 002');
-          expect(element.find('span').scope().$id).toBe('002');
+          expect(element.text()).toBe('Jozo; scopeId: 2');
+          expect(element.find('span').scope().$id).toBe(2);
         }));
 
 
@@ -1919,11 +1919,11 @@ describe('$compile', function() {
               respond('<p><a log>{{name}}; scopeId: {{$id}}</a></p>');
           element = $compile('<div><span trscope></span></div>')($rootScope);
           $httpBackend.flush();
-          expect(log).toEqual('log-002-001; LOG; 002');
+          expect(log).toEqual('log-2-1; LOG; 2');
           $rootScope.name = 'Jozo';
           $rootScope.$apply();
-          expect(element.text()).toBe('Jozo; scopeId: 002');
-          expect(element.find('a').scope().$id).toBe('002');
+          expect(element.text()).toBe('Jozo; scopeId: 2');
+          expect(element.find('a').scope().$id).toBe(2);
         }));
 
 
@@ -1933,12 +1933,12 @@ describe('$compile', function() {
               respond('<p><a log>{{name}}; scopeId: {{$id}} |</a></p>');
           element = $compile('<div><span ng-repeat="i in [1,2,3]" trscope></span></div>')($rootScope);
           $httpBackend.flush();
-          expect(log).toEqual('log-003-002; LOG; 003; log-005-004; LOG; 005; log-007-006; LOG; 007');
+          expect(log).toEqual('log-3-2; LOG; 3; log-5-4; LOG; 5; log-7-6; LOG; 7');
           $rootScope.name = 'Jozo';
           $rootScope.$apply();
-          expect(element.text()).toBe('Jozo; scopeId: 003 |Jozo; scopeId: 005 |Jozo; scopeId: 007 |');
-          expect(element.find('p').scope().$id).toBe('003');
-          expect(element.find('a').scope().$id).toBe('003');
+          expect(element.text()).toBe('Jozo; scopeId: 3 |Jozo; scopeId: 5 |Jozo; scopeId: 7 |');
+          expect(element.find('p').scope().$id).toBe(3);
+          expect(element.find('a').scope().$id).toBe(3);
         }));
 
 
@@ -1947,7 +1947,7 @@ describe('$compile', function() {
           $httpBackend.expect('GET', 'tiscope.html').respond('<a log></a>');
           element = $compile('<div><span tiscope></span></div>')($rootScope);
           $httpBackend.flush();
-          expect(log).toEqual('log-002-001; LOG; 002');
+          expect(log).toEqual('log-2-1; LOG; 2');
           $rootScope.name = 'abc';
           expect(iscope.$parent).toBe($rootScope);
           expect(iscope.name).toBeUndefined();
@@ -1967,7 +1967,7 @@ describe('$compile', function() {
                   '</b>' +
                 '</div>'
               )($rootScope);
-            expect(log).toEqual('002; 003; log-003-002; LOG; log-002-001; LOG; 004; log-004-001; LOG');
+            expect(log).toEqual('2; 3; log-3-2; LOG; log-2-1; LOG; 4; log-4-1; LOG');
           })
         );
 
@@ -1976,7 +1976,7 @@ describe('$compile', function() {
             'the scope', inject(
           function($rootScope, $compile, log) {
             element = $compile('<div class="scope-a; scope-b"></div>')($rootScope);
-            expect(log).toEqual('002; 002');
+            expect(log).toEqual('2; 2');
           })
         );
 
@@ -2012,15 +2012,15 @@ describe('$compile', function() {
         it('should create new scope even at the root of the template', inject(
           function($rootScope, $compile, log) {
             element = $compile('<div scope-a></div>')($rootScope);
-            expect(log).toEqual('002');
+            expect(log).toEqual('2');
           })
         );
 
 
         it('should create isolate scope even at the root of the template', inject(
           function($rootScope, $compile, log) {
             element = $compile('<div iscope></div>')($rootScope);
-            expect(log).toEqual('002');
+            expect(log).toEqual('2');
           })
         );
 
@@ -3871,8 +3871,8 @@ describe('$compile', function() {
           element = $compile('<div><div trans>T:{{$parent.$id}}-{{$id}}<span>;</span></div></div>')
               ($rootScope);
           $rootScope.$apply();
-          expect(element.text()).toEqual('W:001-002;T:001-003;');
-          expect(jqLite(element.find('span')[0]).text()).toEqual('T:001-003');
+          expect(element.text()).toEqual('W:1-2;T:1-3;');
+          expect(jqLite(element.find('span')[0]).text()).toEqual('T:1-3');
           expect(jqLite(element.find('span')[1]).text()).toEqual(';');
         });
       });
@@ -4308,7 +4308,7 @@ describe('$compile', function() {
         inject(function($compile) {
           element = $compile('<div transclude>{{$id}}</div>')($rootScope);
           $rootScope.$apply();
-          expect(element.text()).toBe($rootScope.$id);
+          expect(element.text()).toBe('' + $rootScope.$id);
         });
 
       });
@@ -4544,7 +4544,7 @@ describe('$compile', function() {
               ($rootScope);
           $rootScope.$apply();
           expect(log).toEqual('compile: <!-- trans: text -->; link; LOG; LOG; HIGH');
-          expect(element.text()).toEqual('001-002;001-003;');
+          expect(element.text()).toEqual('1-2;1-3;');
         });
       });
 

test/ng/directive/ngRepeatSpec.js

@@ -976,7 +976,7 @@ describe('ngRepeat', function() {
       scope.items = [a, a, a];
       scope.$digest();
       expect($exceptionHandler.errors.shift().message).
-          toMatch(/^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:003/);
+          toMatch(/^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:3/);
 
       // recover
       scope.items = [a];
@@ -996,7 +996,7 @@ describe('ngRepeat', function() {
       scope.items = [d, d, d];
       scope.$digest();
       expect($exceptionHandler.errors.shift().message).
-          toMatch(/^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:009/);
+          toMatch(/^\[ngRepeat:dupes\] Duplicates in a repeater are not allowed\. Use 'track by' expression to specify unique keys\. Repeater: item in items, Duplicate key: object:9/);
 
       // recover
       scope.items = [a];