The Default policy is: the ChangeDetectionStrategy. Default:

Implementation code:

/**
 * Type of the Directive metadata.
 *
 * @publicApi* /
const Directive = makeDecorator('Directive', ɵ0$e, undefined.undefined, ɵ1$3);
const ɵ2$1 = (c = {}) = > (Object.assign({ changeDetection: ChangeDetectionStrategy. The Default}, c)), ɵ3$1 = (type, meta) = > SWITCH_COMPILE_COMPONENT(type, meta);
/**
 * Component decorator and metadata.
 *
 * @Annotation
 * @publicApi* /
const Component = makeDecorator('Component', ɵ2$1, Directive, undefined, ɵ3$1);
const ɵ4 = (p) = > (Object.assign({ pure: trueɵ}, p))5 = (type, meta) = > SWITCH_COMPILE_PIPE(type, meta);
/ * * *@Annotation
 * @publicApi* /
const Pipe = makeDecorator('Pipe', ɵ4.undefined.undefined, ɵ5);
const ɵ6 = (bindingPropertyName) = > ({ bindingPropertyName });
/ * * *@Annotation
 * @publicApi* /
const Input = makePropDecorator('Input', ɵ6);
const ɵ7 = (bindingPropertyName) = > ({ bindingPropertyName });
/ * * *@Annotation
 * @publicApi* /
const Output = makePropDecorator('Output', ɵ7);
const ɵ8 = (hostPropertyName) = > ({ hostPropertyName });
/ * * *@Annotation
 * @publicApi* /
const HostBinding = makePropDecorator('HostBinding', ɵ8);
const ɵ9 = (eventName, args) = > ({ eventName, args });
Copy the code

In SAP called Spartacus most Component, we will use @ Component changeDetection explicitly specified into ChangeDetectionStrategy. OnPush:



而OnPushIs another strategy for improving the performance of Angular applications.

In OnPush mode, only input ref change and Output’s call trigger the change detection mechanism.

TestBed. OverrideComponent provides a standard that covers ChangeDetectionStrategy mechanism.

More of Jerry’s original articles can be found in “Wang Zixi” :