build_your_own_angularjs_sample

Build Your Own Angular Chapter 1. Scopes And Digest
it("executes $evalAsynced functions added by watch functions", function() {
scope.aValue = [1, 2, 3];
scope.asyncEvaluated = false;
scope.$watch(
function(scope) {
if (!scope.asyncEvaluated) {
scope.$evalAsync(function(scope) {
scope.asyncEvaluated = true;
});
}
return scope.aValue;
},
function(newValue, oldValue, scope) { }
);
scope.$digest();
expect(scope.asyncEvaluated).toBe(true);
});
So what’s the problem As we have seen, we keep running the digest loop as long as
there is at least one watch that is dirty. In the test case above, this is the case in the first
iteration, when we first return scope.aValue from the watch function. That causes the
digest to go into the next iteration, during which it also runs the function we scheduled
using $evalAsync. But what if we schedule an $evalAsync when no watch is actually
dirty
test/scope_spec.js
it("executes $evalAsynced functions even when not dirty", function() {
scope.aValue = [1, 2, 3];
scope.asyncEvaluatedTimes = 0;
scope.$watch(
function(scope) {
if (scope.asyncEvaluatedTimes < 2) {
scope.$evalAsync(function(scope) {
scope.asyncEvaluatedTimes++;
});
}
return scope.aValue;
},
function(newValue, oldValue, scope) { }
);
scope.$digest();
expect(scope.asyncEvaluatedTimes).toBe(2);
});
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