path：packages/shared/ReactSideEffectTags.js

React 副作用标记

源码

export type SideEffectTag = number;// Don't change these two values. They're used by React Dev Tools.export const NoEffect = /*              */ 0b000000000000;export const PerformedWork = /*         */ 0b000000000001;// You can change the rest (and add more).export const Placement = /*             */ 0b000000000010;export const Update = /*                */ 0b000000000100;export const PlacementAndUpdate = /*    */ 0b000000000110;export const Deletion = /*              */ 0b000000001000;export const ContentReset = /*          */ 0b000000010000;export const Callback = /*              */ 0b000000100000;export const DidCapture = /*            */ 0b000001000000;export const Ref = /*                   */ 0b000010000000;export const Snapshot = /*              */ 0b000100000000;export const Passive = /*               */ 0b001000000000;// Passive & Update & Callback & Ref & Snapshotexport const LifecycleEffectMask = /*   */ 0b001110100100;// Union of all host effectsexport const HostEffectMask = /*        */ 0b001111111111;export const Incomplete = /*            */ 0b010000000000;export const ShouldCapture = /*         */ 0b100000000000;复制代码

遗留问题

为什么这些标记要使用二进制数表示？在 React 源码中很多地方使用 |= 的运算符