javascript - angular 2 Do we need avoid two way databind when not necessary? -

i search lot understand if there bad performance if use 2 way databind (ng-model) times @ forms instead of 1 way databind. know angular 1 each 2 way databind new watch created , huge applications angular 1 can have performance issues because this. need know if angular 2 make difference if use 1 way databind or not? 2 way databind need avoid when not necessary?

angular2 doesn't have two-way data binding.

angular2 has

data-binding parent child

[childprop]="parentprop" 

when change detection detects change in parentprop updates childprop , calls ngonchanges() in child component (when implemented).

and event binding child parent

the way child parent event binding.

(childpropchange)="parentprop = $event" 

calls "someactiononparent()" when eventfromchild.emit(somevalue) called in child component.

the combination of these two syntactic sugar data , event bindings shown above

[(childprop)]="parentprop" 

this means change detection has check parentprop change , doesn't care other direction. update child parent has invoked actively child component , doesn't involve change detection.

this unidirectional data flow allows angular2's change detection extremely efficient. further optimize change detection use changedetectionstrategy.onpush in components. allows prune tree angular2 has change detection.