build_your_own_angularjs_sample

Build Your Own Angular Chapter 1. Scopes And Digest
if (!self.$$areEqual(newValue, oldValue, watcher.valueEq)) {
self.$$lastDirtyWatch = watcher;
watcher.last = (watcher.valueEq _.cloneDeep(newValue) : newValue);
watcher.listenerFn(newValue,
(oldValue === initWatchVal newValue : oldValue),
self);
dirty = true;
} else if (self.$$lastDirtyWatch === watcher) {
return false;
}
} catch (e) {
console.error(e);
}
});
return dirty;
};
What remains is exception handling in $evalAsync and $$postDigest. Both are used to
execute arbitrary functions in relation to the digest loop – one before a digest and one
after it. In neither case do we want an exception to cause the loop to end prematurely.
For $evalAsync we can define a test case that checks that a watch is run even when an
exception is thrown from one of the functions scheduled for $evalAsync:
test/scope_spec.js
it("catches exceptions in $evalAsync", function(done) {
scope.aValue = 'abc';
scope.counter = 0;
});
scope.$watch(
function(scope) { return scope.aValue; },
function(newValue, oldValue, scope) {
scope.counter++;
}
);
scope.$evalAsync(function(scope) {
throw "Error";
});
setTimeout(function() {
expect(scope.counter).toBe(1);
done();
}, 50);
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