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å建effect对象ï¼ç»hook对象çmemoizedStateåå å ¥ç»ä»¶fiberçupdateQueueä¸å½¢æeffectç¯ç¶é¾è¡¨ï¼å¨æ¸²æå·¥ä½å®æåï¼ä¼å¾ªç¯è¿ä¸ªç¯ç¶é¾è¡¨ï¼æ§è¡æ¯ä¸ªeffect对象çdestoryåcreateï¼
consteffect={ tag,源码create,destroy,deps,next:null};tagæ¯effectçç±»åtag为9æ¯useEffect,5æ¯useLayoutEffectcreateæ¯useEffectæuseLayoutEffectçåè°å½æ°destroyæ¯createè¿åçåè°å½æ°depsæ¯useEffectæuseLayoutEffectçä¾èµæ°ç»nextæåä¸ä¸ªeffect对象ï¼1.1.effectç¯ç¶é¾è¡¨å¾functionpushEffect(tag,create,destroy,deps){ consteffect={ tag,create,destroy,deps,next:null};//æ°å建çeffect对象为æå为effecté¾è¡¨çä¸ä¸ªeffect对象ï¼componentUpdateQueue.lastEffectä¼æåæ°å建çeffect对象//æ°å建çeffect对象çnextä¼æå第ä¸ä¸ªeffct对象ï¼letcomponentUpdateQueue=(currentlyRenderingFiber.updateQueue);if(componentUpdateQueue===null){ //å½å没æupdateQueuecomponentUpdateQueue=createFunctionComponentUpdateQueue();//å建updateQueuecurrentlyRenderingFiber.updateQueue=componentUpdateQueue;//å½¢æä¸ä¸ªç¯ç¶é¾è¡¨componentUpdateQueue.lastEffect=effect.next=effect}else{ constlastEffect=componentUpdateQueue.lastEffect;if(lastEffect===null){ componentUpdateQueue.lastEffect=effect.next=effect;}else{ //第ä¸ä¸ªeffect对象为æå å建ççeffect对象constfirstEffect=lastEffect.next;//è·å第ä¸ä¸ªeffect对象lastEffect.next=effect;//æ§çæåä¸ä¸ªeffect对象çnextï¼æåæ°å建çeffecteffect.next=firstEffect;//æ°å建çeffect对象çnextæå第ä¸ä¸ªeffectcomponentUpdateQueue.lastEffect=effect;//updateQueueçlastEffectæåeffectï¼æ°å建çeffectå为æåä¸ä¸ªeffect对象}}returneffect;}2.updateEffect页é¢æ´æ°æ¶ï¼æ§è¡updateEffect;
æ ¹æ®hookååé¾è¡¨è·å对åºçæ´æ°æ¶çhook对象ï¼å建æ°çhook对象ï¼å å ¥hookååé¾è¡¨ï¼
å¦æeffectçdepsä¸ä¸ºnullï¼æè undefinedï¼ä¼ä»å½åhook对象æ¿å°ä¸ä¸æ¬¡effect对象ï¼åä»effect对象æ¿å°depsådestroyï¼ç¨æ°çdepsä¸ä¹æ¯è¾ï¼
å¦ææ°èdepsç¸çï¼pushä¸ä¸ªä¸å¸¦HookHasEffectçtagç»effect对象ï¼å å ¥updateQueueç¯ç¶é¾è¡¨ï¼è¿ä¸ªeffectä¸ä¼è¢«æ 记为æå¯ä½ç¨ï¼æ以ï¼effectçcreateådestroyä¸ä¼è¢«æ§è¡ï¼ï¼ä¸æ´æ°hook.memoizedStateï¼
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3.useEffctçåè°å½æ°åéæ¯å½æ°çæ§è¡æ¶æºå¨renderæ¶ææ建effecté¾è¡¨ï¼å¨commitæ¶æ§è¡å æ§è¡ä¹å没ææ§è¡å®çuseEffectï¼ç¶åï¼å¨beforeMutationé¶æ®µæä½domåï¼ä»¥NormalPriority常è§ä¼å 级添å ä¸ä¸ªå¼æ¥ä»»å¡å°ä»»å¡éåï¼è¿ä¸ªå¼æ¥ä»»å¡æ¯ç¨æ¥æ§è¡useEffectçdestroyåcreateçï¼ï¼å¨layouté¶æ®µå®æï¼é¡µé¢å®æ渲æåï¼æ§è¡å¨beforeMutationé¶æ®µæ·»å çå¼æ¥ä»»å¡ï¼
3.1.commitå¼å§æ¶ä¸»è¦æ¯ä¸ºäºæ§è¡ä¹å没ææ§è¡çuseEffect
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functioncommitRootImpl(root,recoverableErrors,renderPriorityLevel){ do{ //`flushPassiveEffects`willcall`flushSyncUpdateQueue`attheend,which//means`flushPassiveEffects`willsometimesresultinadditional//passiveeffects.Soweneedtokeepflushinginaloopuntilthereare//nomorependingeffects.//TODO:Mightbebetterif`flushPassiveEffects`didnotautomatically//flushsynchronousworkattheend,toavoidfactoringhazardslikethis.flushPassiveEffects();}while(rootWithPendingPassiveEffects!==null);...çç¥ä»£ç }3.2.beforeMutationåªä¼åèµ·ä¸æ¬¡useEffectè°åº¦ï¼æ¯å¼æ¥è°åº¦ï¼ä»¥NormalPriority常è§ä¼å 级添å ä¸ä¸ªå¼æ¥ä»»å¡å¨ä»»å¡éåä¸ï¼push(timerQueue,newTask)ï¼ï¼å¨é¡µé¢æ¸²æå®ææ¶ï¼ä¼æ§è¡è¿ä¸ªå¼æ¥ä»»å¡
functioncommitRootImpl(root,recoverableErrors,renderPriorityLevel){ ...çç¥ä»£ç if((finishedWork.subtreeFlags&PassiveMask)!==NoFlags||(finishedWork.flags&PassiveMask)!==NoFlags){ if(!rootDoesHavePassiveEffects){ rootDoesHavePassiveEffects=true;scheduleCallback$1(NormalPriority,function(){ //æ·»å ä¸ä¸ªå¼æ¥ä»»å¡å°ä»»å¡éåflushPassiveEffects();//Thisrendertriggeredpassiveeffects:releasetherootcachepool//*after*passiveeffectsfiretoavoidfreeingacachepoolthatmay//bereferencedbyanodeinthetree(HostRoot,Cacheboundaryetc)returnnull;});}}...çç¥ä»£ç }3.3.layoutå è½½æ¶ï¼åªæ§è¡useEffectçcreateå½æ°å³å¯ï¼
å¦æpendingPassiveEffectsLanesæ¯åæ¥èµéï¼å°±å¨é¡µé¢æ¸²æå®ç´æ¥æ§è¡useEffectçcreateådestroyï¼å¨beforeMutationæ¶æ·»å çå¼æ¥ä»»å¡ï¼ä¸ä¼æ§è¡useEffectçcreateådestory
if(includesSomeLane(pendingPassiveEffectsLanes,SyncLane)&&root.tag!==LegacyRoot){ //å è½½æé´é»è®¤æ¯ä¸èµ°è¿éç//è¿éä¹æ¯æ§è¡useEffectçcreateï¼å¦æpendingPassiveEffectsLanesæ¯åæ¥èµéï¼//å°±å¨æ¸²æå®æåç´æ¥æ§è¡useEffectçcreateådestory//å¨beforeMutationæ¶æ·»å çå¼æ¥ä»»å¡æ§è¡æ¶ï¼ä¸ä¼æ§è¡useEffectçcreateådestoryflushPassiveEffects();}æ§è¡ä¸ä¸æ¬¡useEffectçcreateè¿åçdestroyï¼æ¿å°å½æ°ç»ä»¶fiberçupdateQueueï¼å¾ªç¯è¿ä¸ªeffectç¯ç¶é¾è¡¨ï¼æ¿å°effect对象çdestroyæ§è¡ï¼
functioncommitHookEffectListUnmount(flags,finishedWork,nearestMountedAncestor){ varupdateQueue=finishedWork.updateQueue;varlastEffect=updateQueue!==null?updateQueue.lastEffect:null;if(lastEffect!==null){ varfirstEffect=lastEffect.next;vareffect=firstEffect;do{ if((effect.tag&flags)===flags){ //Unmountvardestroy=effect.destroy;effect.destroy=undefined;if(destroy!==undefined){ { if((flags&Passive$1)!==NoFlags$1){ markComponentPassiveEffectUnmountStarted(finishedWork);}elseif((flags&Layout)!==NoFlags$1){ markComponentLayoutEffectUnmountStarted(finishedWork);}}safelyCallDestroy(finishedWork,nearestMountedAncestor,destroy);//æ§è¡destroy{ if((flags&Passive$1)!==NoFlags$1){ markComponentPassiveEffectUnmountStopped();}elseif((flags&Layout)!==NoFlags$1){ markComponentLayoutEffectUnmountStopped();}}}}effect=effect.next;}while(effect!==firstEffect);}}æ§è¡å®ææç»ä»¶çdestroyï¼åæ§è¡createï¼åçï¼ä¹æ¯æ¿å°å½æ°ç»ä»¶fiberçupdateQueueï¼å¾ªç¯è¿ä¸ªeffectç¯ç¶é¾è¡¨ï¼æ¿å°effect对象çcreateæ§è¡ï¼ç¶åæcreateè¿åçdestroyç»effect对象ï¼ççä¸çæ´æ°æ§è¡useEffectæ¶ç¨ï¼ï¼
functioncommitHookEffectListMount(flags,finishedWork){ varupdateQueue=finishedWork.updateQueue;varlastEffect=updateQueue!==null?updateQueue.lastEffect:null;if(lastEffect!==null){ varfirstEffect=lastEffect.next;vareffect=firstEffect;do{ if((effect.tag&flags)===flags){ { if((flags&Passive$1)!==NoFlags$1){ markComponentPassiveEffectMountStarted(finishedWork);}elseif((flags&Layout)!==NoFlags$1){ markComponentLayoutEffectMountStarted(finishedWork);}}//Mountvarcreate=effect.create;effect.destroy=create();{ if((flags&Passive$1)!==NoFlags$1){ markComponentPassiveEffectMountStopped();}elseif((flags&Layout)!==NoFlags$1){ markComponentLayoutEffectMountStopped();}}{ vardestroy=effect.destroy;if(destroy!==undefined&&typeofdestroy!=='function'){ varhookName=void0;if((effect.tag&Layout)!==NoFlags){ hookName='useLayoutEffect';}elseif((effect.tag&Insertion)!==NoFlags){ hookName='useInsertionEffect';}else{ hookName='useEffect';}varaddendum=void0;if(destroy===null){ addendum='Youreturnednull.Ifyoureffectdoesnotrequireclean'+'up,returnundefined(ornothing).';}elseif(typeofdestroy.then==='function'){ addendum='\n\nItlookslikeyouwrote'+hookName+'(async()=>...)orreturnedaPromise.'+'Instead,writetheasyncfunctioninsideyoureffect'+'andcallitimmediately:\n\n'+hookName+'(()=>{ \n'+'asyncfunctionfetchData(){ \n'+'//Youcanawaithere\n'+'constresponse=awaitMyAPI.getData(someId);\n'+'//...\n'+'}\n'+'fetchData();\n'+"},[someId]);//Or[]ifeffectdoesn'tneedpropsorstate\n\n"+'LearnmoreaboutdatafetchingwithHooks:/post/web前端自学要多久?
主要看你之前是否有接触过前端,是源码否有些前端基础,另外还要看你的源码接受能力以及是否喜欢这个专业。如果接受对力尚佳,源码视频试看 源码或者有些前端基础,源码天到1个月就差不多能够入门。源码电子请柬平台源码如果慢一些的源码,三个月也差不多了。源码但是源码这只能说是一个基础部分,找工作是源码找不到的。
接下来就是源码需要再深入系统地学习,再学习一些前端自动化,源码一些流行的源码app商城java源码框架,还要稍微懂些node知识等,源码如果学习能力强并且自制力强的源码话,大概一共需要5个月的捷径查看网页源码时间。当然这期间需要做大量的实践与练习,来巩固基础知识。
如果是openid网站获取源码零基础,并且自控力不强,还是建议报一个培训班,系统学习一下前端知识,把基础知识打扎实了,将来的学习会很简单。不管框架如何改变,都万变不离其宗的。如果基础知识不扎实,框架日新月异,会感到很吃力。
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