priority.md

React 优先级

二进制表示法

源码

function getLabelForLane(lane) {
  if (lane & 1) return 'SyncHydrationLane';
  if (lane & 2) return 'Sync';
  if (lane & 4) return 'InputContinuousHydration';
  if (lane & 8) return 'InputContinuous';
  if (lane & 16) return 'DefaultHydration';
  if (lane & 32) return 'Default';
  if (lane & 64) return 'TransitionHydration';
  if (lane & 4194176) return 'Transition';
  if (lane & 62914560) return 'Retry';
  if (lane & 67108864) return 'SelectiveHydration';
  if (lane & 134217728) return 'IdleHydration';
  if (lane & 268435456) return 'Idle';
  if (lane & 536870912) return 'Offscreen';
  if (lane & 1073741824) return 'Deferred';
}

function getHighestPriorityLanes(lanes) {
  var pendingSyncLanes = lanes & 42;
  if (0 !== pendingSyncLanes) return pendingSyncLanes;
  switch (lanes & -lanes) {
    case 1:
      return 1;
    case 2:
      return 2;
    case 4:
      return 4;
    case 8:
      return 8;
    case 16:
      return 16;
    case 32:
      return 32;
    case 64:
      return 64;
    case 128:
    case 256:
    case 512:
    case 1024:
    case 2048:
    case 4096:
    case 8192:
    case 16384:
    case 32768:
    case 65536:
    case 131072:
    case 262144:
    case 524288:
    case 1048576:
    case 2097152:
      return lanes & 4194176;
    case 4194304:
    case 8388608:
    case 16777216:
    case 33554432:
      return lanes & 62914560;
    case 67108864:
      return 67108864;
    case 134217728:
      return 134217728;
    case 268435456:
      return 268435456;
    case 536870912:
      return 536870912;
    case 1073741824:
      return 0;
    default:
      return console.error('Should have found matching lanes. This is a bug in React.'), lanes;
  }
}

SyncLane

对应调度器优先级	描述	二进制
ImmediatePriority (99)	优先级最高，需要及时响应的操作	0b00000000000000000000000001

InputContinuousLane

对应调度器优先级	描述	二进制
UserBlockingPriority (98)	连续响应的操作（滚动，拖拽）	0b00000000000000000000000100

DefaultLane

对应调度器优先级	描述	二进制
NormalPriority (97)	默认行为（useState, useReducer, useEffect）	0b00000000000000000000010000

TransitionLane

对应调度器优先级	描述	二进制
NormalPriority (97)	可延迟的非关键更新（数据加载，页面跳转）	0b00000000000000000000010000

RetryLane

对应调度器优先级	描述	二进制
LowPriority (96)	Suspense 重试或任务恢复	0b00000000000000100000000000

IdleLane

对应调度器优先级	描述	二进制
IdlePriority (95)	完全不影响交互的后台任务（日志上报、预加载）	0b00100000000000000000000000