JavaScript: hloov cov ntaub ntawv - xaiv xaiv

Yog vim li cas yog ib txwm zoo li qub, qhov tseem ceeb yog tej zaum ib tug ntau. Los yog vice versa: ib tus nqi yuav muaj ob peb yog vim li cas rau nws tshwm sim. Nyob rau hauv txhua rooj plaub, nyob ntawm seb tej yam tej yam kev mob yuav tsum tau tsuas yog ib cov kua, los yog vice versa.

Txawm hais tias qhov kev txiav txim tej zaum yuav muaj ob peb xaiv rau tej lub hom phiaj yuav ua tau tsuas yog ib txoj kev, tiam sis feem ntau ob peb txoj kev, thiab peb yuav tsum tau mus ua ib tug xaiv.

Classic nqe lus yog hais tias (mob) {1 algorithm, yog hais tias tus mob yog muaj tseeb} lwm {2 algorithm, yog hais tias tus mob yog cuav} muab tsuas yog ob tug xaiv. Tab sis txawm ib tug yooj yim tiag tiag kev sib tw yeej ib txwm muab ib tug ntau ntawm kev xaiv.

Ib tug yooj yim "tsis muaj ib tug", tab sis ib yam kev mob

JavaScript Design, hloov cov ntaub ntawv = ntau qhov tseem ceeb rau cov neeg mob. Yuav tau siv ib tug zoo xws li cov Yog hais tias tus neeg tsav tsheb ob peb ua ke. Txawm li cas los, unquestionably, thawj embodiment ntawm syntactically thiab semantically ntau lawm. Nyob rau hauv tas li ntawd, ib tug formal kev txiav txim siab nyob rau hauv lub thib ob version yuav yuav tsum tau ntau kev txawj tsim tawm:

Muaj ke, yog hais tias (...) {...} lwm {...} thiab sim {...} cath (...) {...} muab sab saum toj AJAX-pauv txoj kev nyob rau hauv lub algorithm. teb ua yog ua zoo xws li cov txheej conditional cov nqe lus.

JavaScript hloov cov ntaub ntawv: ib qho piv txwv

Lub ntsiab lwm txawv xaiv ib qho kev xaiv los ntawm ib yam kev mob: koj tsis tau sau ob tug, thiab ib tug ob peb blocks ntawm executable commands. Nws yuav tsum tseg ib zaug xwb los yog tsuas yog ob peb tug.

Qauv J avaScript hloov cov ntaub ntawv tso cai rau muab ib tug plurality ntawm algorithms nyob rau ntawm tus nqi ntawm ib tug nce mus nce los los yog ib qho kev qhia. Nws yog ib qho tseem ceeb los ua tim nyob rau hauv lub siab hais tias qhov tseeb kev xaiv ntawm lub algorithm yuav ua rau pes tsawg match nyob rau hauv cov nqe lus ntawm cov nqi mus () thiab tus nqi ntawm dab tsi yog hais nyob rau hauv cov ntaub ntawv. Lub "1" thiab tus naj npawb 1 - qhov no hom hloov dua siab tshiab yog tsis tau no tsis yog tib yam.

Ua ntau seem

Ib tug yam ntxwv feature ntawm tus tsim cov kev xaiv J avaScript hloov cov ntaub ntawv yog qhov uas tsis nkhaus blocks - {...} entrusted rau txhais tsuas yog thaum pib thiab thaum xaus ntawm lub xov tooj lub cev. Txhua seem terminates cov ntaub ntawv so neeg teb xov tooj, uas tej zaum yuav tsis tau.

Nyob rau hauv cov piv txwv raug hla lawm so nyob rau hauv thawj cov ntaub ntawv seem. Option nyob rau sab laug yuav muab cov Variant2, vim hais tias nws yog no uas pib lub tiav, thiab nyob rau hauv lub embodiment ntawm txoj cai yuav tsum tau txais Variant1Variant2, raws li nws yuav ua tau tus thawj, tab sis tsis ntxim yog tus thib ob mob, thiab dua li, tsis muaj dab tsi tiv thaiv rau txim tuag nqe lus ntawm cov thawj tshooj lus no, ces thib ob, nruab nrab ntawm lawv yog tsis muaj neeg teb xov tooj so, tab sis ob zaug JavaScript hloov cov ntaub ntawv tsis tau. Nws yuav tsum tau muab sau tseg tias kev hloov nyob rau hauv lub nce mus nce los iCond nyob rau hauv lub cev cov qauv tsis muab tej yam nyhuv.

Code ib tug kev muaj tiag thiab cov kev muaj tiag ntawm qhov teeb meem

JavaScript - cov lus ntawm ib tug kuj zoo kawg, ceev, cos thiab cov zajlus kom nrog lub siv syntax. JavaScript hloov cov ntaub ntawv tsim txig xwb, uas tseeb thiab yog piav qhia ntawm yam ntau yam ntawm cov kev xaiv ntawm kev mob.

Neeg teb xov tooj xaiv tej zaum yuav muab tso rau hauv txhua lwm yam. Nyob rau hauv cov ntaub ntawv ntawm cov seem tej zaum yuav nyob ntawm nqe lus, loops, lwm yam lug. Peb yuav tsum tsis txhob tsis saib tsis xyuas lub Scope ntawm cov tsiaj ntawv. Raws li siv qhov txhia chaw nws yog piav thoob ntiaj teb.

Txawm li cas los, nws yuav tsum tsis txhob ua phem rau JavaScript. Hloov cov ntaub ntawv - ib tug zoo twj ceg, tab sis tsis nyob rau hauv lub high-volume mobile code. Cov txawj xav thiab tej kab kev los ntawm cov kev xaiv siv, qhov ntau nyuaj nws yuav tsum tau hloov tom qab.

Qhov tiag kev sib tw yeej yuav tsis sawv tseem, thiab yog hais tias koj tsis coj mus rau hauv tus account hloov nyob rau hauv lub chav kawm ntawm nws cov kev txiav txim siab, tias txij li thaum kawm tiav ntawm lub chaw ua hauj lwm, nyob rau hauv thawj hnub ntawm lub lag luam los tsim ib qho chaw yuav khees inaccuracies thiab omissions. Cov kev sib tw, ntawm chav kawm, yuav mus rau pem hauv ntej, thiab lub site yuav tsum tau tiav lawm.

Los ntawm no foundations, lub ntsiab disadvantage ntawm JavaScript hloov cov ntaub ntawv derives los ntawm nws loj thiab complexity. Yog hais tias koj tsis ua phem rau nws, koj muaj peev xwm ua tau mus ua ib tug compact thiab me me xaiv.

Mob + tshuaj = tshiab round zog

Puas tu yog formulated teeb meem approximates cov tshuaj. Txawm tias qhov teeb meem no, los ntawm txhais, nws tus kheej tsis tau daws tau ib yam dab tsi, thiab zoom.

Tus mob no yog siv qhov txhia chaw (private me me hauj lwm). tej yam kev mob ntawm tua = tua ntawm ib co code. Siv rau JavaScript hloov cov ntaub ntawv - nws yog ib tug zam daim ntawv qhia, thiab ib cov ntshiab yuav tsum tau. Txij li thaum tau ua nyob rau hauv tag nrho cov lus, vim hais tias nws yog yooj yim thiab yooj yim.

Thaum yug "Lisp" thiab "Prologue", zoo ib yam li lawv cov programming lus. Muaj battles tshaj txoj kev hloov tswv thiab cov ntawv. Kuv sim kom tau ib tug dlej duas kev haumxeeb style ntawm kev sau ntawv cov kev pab cuam. Niaj hnub no, loj heev tsim tawm enthusiastically txhawb yam khoom-taw qhia kom paub cov tswv yim.

Txawm li cas los, kom txog thaum uas tam sim no nyob rau hauv niaj hnub ua hauj lwm nrhiav tau lawv qhov tseem ceeb nyob ntawm cov nqe lus. Tab sis lub essence ntawm niaj hnub lub tswv yim nyob rau hauv lub fact tias cov khoom lawv tus kheej teem tej yam kev mob thiab nrhiav kev dlaws. Tom qab tag nrho, tus kwv - ib tug txheej ntawm syntax thiab semantics.