Javascript Elifanayo ukugcina inani mda nesebenzayo

JavaScript - ulwimi isikhangeli, kuba asingabo bonke ingxaki ifuna izinto zayo, kwimiboniso kunye izinto. Kwiimeko ezininzi kwanele ukusebenzisa nje DOM (Document Object Model). Kodwa kwiimeko ezinjalo, inkcazo ngokuchanekileyo data esetyenziswa usoloko yenza inkqubo egqibeleleyo, ukuphuculwa lula-to-ukusetyenziswa kunye ezilandelayo.

amagama abalulekileyo, kodwa, wayebhekisela inkqubo eza kusetyenziswa kunye notshintsho, kufanelekile ukuba ukunciphisa "data 'amagama' variables". Oh noko baza kubakho - JavaScript Array, Object, okanye nje elipheleleyo - kuxhomekeke ingxaki, okanye mandithi ukusuka kwindawo ethile kuso.

ikhowudi logic data

Program kusetyenziswa ukulawula data. Kwakukho kwaye ezinye izinto ngeendlela ezininzi izimvo (imigca, iisimboli, amanani, imihla, ...), njengoko umthetho, kwimiboniso ngokwahlukileyo entle, kwaye (i sibini lokugqibela eminyaka) izinto.

Kwindawo ethile ngexesha ukuchwetheza data olungqongqo sele amazwi, kwaye ngoku ngolwimi zonke mihla, oku ungatshintsha kuphela umxholo kodwa uhlobo. Elungileyo okanye embi, kuya kuba ibonakale, kodwa zokuChwetheza esinamandla iimpawu zayo ezintle. Nakuba kunjalo, ukuba oku kwenzeka, ngoko kutheni "rastipirovat 'yonke le nkqubo?

Ngokwamanani lwesemantiki, okt ngaphandle lwesivakalisi, nayiphi variable has ixabiso. Kwaye kuyo nayiphi na imeko yemicimbi iyatshintsha. Ulandelelwano utshintsho - sisixa, ngokwemigaqo ye JavaScript - element uluhlu.

Ngamanye amazwi, ukuba wenkqubo igqibe nokutyeshela uhlobo variable wazibeka ulwimi ulixhalabele ukuguquka eyiyo ngexesha kweentlobo, kutheni musa lula: kukho nje data, kakuhle, singasathethi ke yintoni na kwindawo yesicelo - inani, umtya, uluhlu, okanye intoni - yiloo ikhowudi ukuyisombulula. Okunye ngokuchanekileyo: oku kufuneka ngokwayo amisele ukuba yintoni na onokuyenza ngayo nendlela.

data Simple nolwamagama

variables Simple iintlobo ezahlukeneyo. nokuguqulwa Uhlobo zenziwa ngokuzenzekela xa kukho imfuneko yoko.

Lo mzekelo uchaza s elula variable, apho umphumo iya kuyilwa kunye JavaScript Array aCheck. Le i variable uchazwa ngqo kumjikelo operation aCheck. Apha, izinto uluhlu (wadala ngokusebenzisa Yakhani uluhlu lokutyhala isakhiwo JavaScript) ukumela amaxabiso ezintathu kweentlobo ezahlukeneyo. Ovelisa kumjikelo wokuqala emgceni s uhlobo igama, okwesibini - ngamaxabiso okwenene. ukuguqulwa kohlobo kuyakuqhubeka.

Malunga inani izakhi amaqoqo

Le Elifanayo JavaScript ayikho into uluhlu associative. Weposi onikeza izinto usebenzisa amaqhosha lwamanani, inani eliphezulu lweziqalelo - 2 ^32, kodwa ukuba zizame umda inani lezinto kufuneka kungabi.

algorithm Good isoloko inani kwangoku Dunn kunye JavaSscript uyilo ubude Array lwaqaliswa lwesivakalisi ayikho ukulawula ivolyum uluhlu kwimeko ngezinto ezilapho kuyo.

ixabiso aCheck.length ayisoloko nelona nani lweziqalelo. Le Elifanayo JavaScript anokuqulatha ezininzi kwaye kukho sele ithunyelwe, kodwa ukuze ufumanise ukuba kanye kangakanani, ngamanye amaxesha kufuneka sisebenze nzima.

Kulo mzekelo, ibinzana aCheck [5] kwandisa uluhlu lweziqalelo ezintandathu. Kondla ithemba lokuba ubude hlobo luza kukunika ixabiso ka-4, akagwetyelwa.

ma associative

Ngokusemthethweni JavaScript Array kunokuba kuphela eziqhelekileyo, oko kukuthi, izinto zifumaneka yi index wokwamanani. Kodwa ke eneneni, unga sebenzisa izimvo associative.

umsebenzi olula kakhulu kwaye zokuphila ukuhlela imiqolo ziintsika etafileni ingasombululwa yi uluhlu associative. Point kwi isangqa ecaleni kwegama kwikholam kuthetha akukho uhlelwe, utolo - ekwehleni, utolo ezantsi - inyuka. Nqakraza kwi namali yomhlathi (ukhetho realiatsii kwi JavaScript: Hlela Array).

Kulo mzekelo, kukho uluhlu eyenziwe cSortCols okhetho kwiindawo ngu kumhlathi ngamnye (S, C, W, ...). Iinqobo ndlela u kuphela, d. Uyilo Ngokuba zonke ligated kwi enye emgceni (kwikholamu ikhowudi, kunye ubeko lwesikhombiso). Lo mjikelo lijonga zoonke uluhlu, kwaye sebenzisa i JavaScript ubude Array ayikho imfuneko.

Ukuyila kwaye uluhlu nokuhlela kwi JavaScript

amava Beautiful - bhala 'var xMass = [];' okanye 'var yArr = {};'. Kwimeko yokuqala, uluhlu njengesiqhelo baya kumiselwa, kwimeko yesibini - associative. Sebenzisa ukhetho JavaScript New Array () Kwakhona kuyenzeka, kodwa ngokuqhelekileyo esi sakhiwo asetyenziselwa ezinye iinjongo, ingakumbi ukusebenza izinto.

Yenza uluhlu, ungenza ngokukhawuleza niwuzalise eziguquguqukayo, kodwa umthetho, ukuzaliswa kanye, ukukhohlisa uluhlu dynamically, ngexesha ukuphunyezwa kwale nkqubo. Ukuba kuyimfuneko, ungasebenzisa ubeko JavaScript uyilo Uhlobo Array, nto leyo ayikho bhetyebhetye kakhulu, kodwa ikuvumela ukulawula inkqubo ngokusebenzisa imisebenzi yayo.

Tsalela: arr.sort () kukhokelela ubeko amacwecwe ASCII balinganiswa balandelayo le nkqubo. Umsebenzi eguqulweyo ngokubaxwa i - elements kweKhabhinethi: arr.reverse (). Lo msebenzi lutshintsha indlela izakhi uluhlu kwi umva.

Kuzo zombini ezi meko, eli gama libhekisela Fika uluhlu. Kwimeko yokuqala kuvunyelwa ukuba basebenzise zabo lokhetho umsebenzi, oko kukuthi arr.sort umngeni (myfunc (a, b)) iya kubangela ufowuna umsebenzi wakho myfuct yakhe, ekufuneka unike isiphumo kuxhomekeka data: a kunye b. Ukuba ujonga ngaphantsi kwe owesibini, ngoko 1, ukuba okwahlukileyo yi-1, kwaye ukuba = b, ngoko 0. Apha uthelekiso kwingongoma nganye iya kumiselwa wenkqubo kumsebenzi myfunc.

Ingcamango i element esebenzayo

Lo msebenzi ukubiza kwi yokuhlela inkqubo, uyakwazi ukwenza iintshukumo ezahlukeneyo. Ngokwembono yoyilo, esebenzisa, oku akulindelekanga ukuba baphendule igalelo parameters, yaye isiphumo - hayi amanani amathathu kuphela 1, 1 0 kwi uluhlu isicelo cyclically yonke into, oko lungisa uluhlu.

Ukuba simele sicinge ukuba uluhlu - kuba ingqiqo ethile, into ethile isakhiwo data, ngoko ke Array JavaScript iguqulelwa ezinomthamo ezahlukeneyo variable.

Ukuba uthathe njengesiseko ukusetyenziswa yokuqala okanye element yokugqibela uluhlu njenge umxholo wayo thina, ukuba enze umsebenzi uhlobo unako ukuguqula afanayo ukuze Into yokuqala / bokugqibela baya kuba ezahlukeneyo, njengoko kufunwa yi nemiqathango ngxaki.

Le mbono unokuvumela izisombululo ngokutsha algorithm ngaloo ndlela, ingakumbi ukuba akukho mfuneko elide ukusebenzisa yoyilo ukuba () {} enye {} kwaye switsha () {kwimeko '': ...; case '': ...; ...}.

Ngokwenza umxholo uluhlu, ungasa imiba ngaphakathi kwayo, ngokwenjenjalo ukutshintsha ukusebenza yangaphandle, leyo luza kufumaneka ngokusebenzisa yokuqala okanye into yokugqibela.

Yakhani uluhlu JavaScript: sebenzisa engenangqondo

Wonke ulwimi ulungile kuba kukuvumela nje ukutshintsha isakhiwo kunye nesiqulatho i data, kodwa i ikhowudi ngqo. Ingcamango ingqalelo mahluko njengento nomda, okt ekuqaleni ngaphandle kokunika isimo yayo generic, bavula lawo ezintsha.

Eqala ukuthatyathwa, variable, uluhlu okanye into uvumele wena ukungenisa lweenkcukacha njengoko umsebenzi zezi data, kunye namandla.

Umzekelo, ukufunda isicatshulwa, sinako ukuchaza le "umbhalo", nto leyo iza kwahlulwa ibe isindululo - uvavanyo ze 'indawo "(kwimeko, oko kukuthi, kuthathelwa ingqalelo syntax izivakalisi). Izindululo uya kuqhiphuka umbilini zibe amabinzana (kwimeko, kwekoma kwaye lwesivakalisi efanelekileyo). amagama kunye neeleta.

Isiphumo: unako ukusebenza kwinqanaba itekisi, izivakalisi, amagama. Kwinqanaba ngalinye, ungenza ukudala umsebenzi "nokwahluka", nto leyo eza kukhangela ukuba efanayo okanye obufanayo. Unako ukudala umsebenzi isicelo lwezivakalisi, Amabinzana enye idatha.

iinkqubo Modern ixesha elide ayikho imfundiso, kodwa kukuba kule minyaka ilishumi idlulileyo ngenxa isakhiwo syntactic kunye namava wavula zexa amatsha abaphuhlisi iilwimi engacwangciswanga - kodwa ukuba yafunyanwa kwaye isetyenziswe.