Video: Yuav ua li cas yog deferred scripts hauv JavaScript?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Cov ncua attribute qhia rau tus browser tias nws yuav tsum mus ua haujlwm nrog nplooj ntawv, thiab thauj khoom tsab ntawv "nyob rau hauv keeb kwm yav dhau", ces khiav lub tsab ntawv thaum nws loads. Cov ntawv nrog ncua yeej tsis thaiv nplooj ntawv. Cov ntawv nrog ncua ib txwm ua thaum DOM npaj txhij, tab sis ua ntej DOMContentLoaded tshwm sim.
Kuj kom paub yog, dab tsi yog ncua hauv JavaScript?
Kev cog lus yog qhov chaw rau qhov tshwm sim uas yog thawj zaug tsis paub thaum a ncua sawv cev rau kev xam uas ua rau tus nqi. Thaum cov lus cog tseg yog tus nqi xa rov qab los ntawm kev ua haujlwm asynchronous, a ncua tuaj yeem daws lossis tsis lees paub los ntawm nws tus neeg hu xov tooj uas cais cov lus cog tseg los ntawm tus neeg daws teeb meem.
Qhov thib ob, dab tsi yog async defer hauv JavaScript? Async vs Defer Nrog async , cov ntaub ntawv tau downloaded asynchronously thiab ces tua sai li sai tau thaum nws yog downloaded. Nrog ncua , cov ntaub ntawv tau rub tawm asynchronously, tab sis tsuas yog ua tiav thaum cov ntaub ntawv parsing tiav. Nrog ncua , scripts yuav ua tib yam li lawv hu.
Raws li txoj cai, qhov txawv ntawm asynchronously loading ib tsab ntawv thiab ncua kev thauj khoom ntawm cov ntawv sau?
Cov qhov sib txawv ntawm async thiab ncua centers nyob ib ncig ntawm thaum lub tsab ntawv raug tua. Txhua async tsab ntawv executes ntawm thawj lub sijhawm tom qab nws tiav rub tawm thiab ua ntej lub qhov rais thauj xwm txheej. Raws li qhov ncua scripts , ntawm qhov tod tes, tau lees tias yuav raug tua hauv xaj lawv tshwm sim hauv nplooj.
Yuav ua li cas ntxiv defer hauv JavaScript?
Cov DEFER Txoj Kev Koj ua tau ntxiv lub ncua ” tus cwj pwm rau txhua qhov ntawm koj lub cim npe sab nraud. Dab tsi yog ' ncua ' attribute puas yog qhia lub web browser kom tsis txhob thauj nws mus txog thaum HTML tau ua tiav kev thauj khoom.
Pom zoo:
Yuav ua li cas txheeb xyuas qhov sib txawv yog null hauv JavaScript?
Teb: Siv tus neeg teb xov tooj sib npaug (==) Whereas, qhov null yog tus nqi tshwj xeeb, uas tuaj yeem raug xa mus rau qhov sib txawv raws li qhov sawv cev tsis muaj nqi. Hauv cov lus yooj yooj yim koj tuaj yeem hais tus nqi tsis muaj nqi txhais tau tias tsis muaj nqi lossis tsis muaj tus nqi, thiab undefined txhais tau tias qhov sib txawv uas tau tshaj tawm tab sis tseem tsis tau muab tus nqi
Yuav ua li cas yog ib tug txheej txheem nyob rau hauv lub operating system dab tsi yog ib tug xov nyob rau hauv lub operating system?
Ib tug txheej txheem, nyob rau hauv cov nqe lus yooj yim tshaj, yog ib tug executingprogram. Ib tug los yog ntau tshaj threads khiav nyob rau hauv cov ntsiab lus ntawm cov txheej txheem. Ib tug xov yog ib qho tseem ceeb chav tsev uas theoperating system faib lub sij hawm processor. Lub threadpool feem ntau yog siv los txo tus naj npawb ntawm cov ntaub ntawv thov thiab muab kev tswj hwm ntawm cov neeg ua haujlwm threads
Kuv yuav siv Google scripts hauv Gmail li cas?
Kauj ruam 1: Tsim tsab ntawv. Tsim ib tsab ntawv tshiab los ntawm kev mus rau script.google.com/create. Hloov cov ntsiab lus ntawm cov ntawv sau nrog cov cai hauv qab no: Kauj Ruam 2: Qhib Gmail API. Qhib GmailAPI cov kev pabcuam siab tshaj hauv koj tsab ntawv. Kauj ruam 3: Khiav tus qauv. Hauv Apps Script editor, nyemRun> listLabels
Dab tsi yog deferred object hauv Javascript?
Qeb: Deferred Object Lub Deferred object, qhia nyob rau hauv jQuery 1.5, yog ib tug chainable utility khoom tsim los ntawm hu rau lub jQuery. Deferred() method. Nws tuaj yeem sau npe ntau callbacks rau hauv callback queues, invoke callback queues, thiab relay qhov kev vam meej lossis tsis ua haujlwm ntawm ib qho kev ua haujlwm synchronous lossis asynchronous
Yuav ua li cas koj tig ib txoj hlua rau hauv array hauv JavaScript?
Cov hlua hauv JavaScript tuaj yeem hloov mus rau hauv cov cim array los ntawm kev siv cov split() thiab Array. los ntawm ( ) ua haujlwm. Siv String split() Function: Lub str. split() muaj nuj nqi yog siv los faib cov hlua muab rau hauv array ntawm cov hlua los ntawm kev cais nws mus rau hauv substrings siv ib qho kev cais cais muab rau hauv qhov kev sib cav