それは、このここに(テンプレートの構文セクション)の話をするとき、正確例えば、Angular2ドキュメントの「副作用」によって意味するものは私のために完全には明らかではありません:式の評価は副作用がありますどのように
Angular2のドキュメントで「副作用」とはどういう意味ですか?
Avoid side effects
As mentioned previously, evaluation of a template expression should have no visible side effects. The expression language itself does its part to keep you safe. You can't assign a value to anything in a property binding expression nor use the increment and decrement operators.
Of course, the expression might invoke a property or method that has side effects. Angular has no way of knowing that or stopping you.
The expression could call something like getFoo(). Only you know what getFoo() does. If getFoo() changes something and you happen to be binding to that something, you risk an unpleasant experience. Angular may or may not display the changed value. Angular may detect the change and throw a warning error. In general, stick to data properties and to methods that return values and do no more.
とこれがUIプレゼンテーションやロジックにどのように影響するのでしょうか?