JavaScript: typeof - faniro kana mukana

Akashandisa kuva imwe mhando data, uye aiva kufarira kugadzira dzavo kuti vawane mugumisiro. The kutonga kuti "pfungwa atypical mu Rondedzero" pakarepo, asi kwoga. Pre-shanduka Kuzivisa hachisisiri madikanwa, uye chiratidzo chacho mhando zvavo varasikirwa zvinoreva zvose, dzinenge kune kushanda nayo chikamu.

Programmer akasunungura maoko ake; hakusi zvakakodzera kuzivisa chinhu pakutanga. Kazhinji chete panguva kushandiswa richava kuona chii kutora, kuita uye sei. Kana mifananidzo, ivo pachavo "vava tsika," kureva kuti anova mashoko pamusoro izvo inobvawo pane chimwe chinhu!

It ane kana asina, zvakanaka, chii chacho

tsananguro A nyore kwazvo shanduka 'AAA "uye iripo algorithm kuti kugadzira:

aaa ; hadde AAA;

( aaa ) { kana (AAA) {
= 'I am!' Res = 'Ndini!' ; // NDIRI!
{ } Else {
= 'me no...' ; Res = 'ini kwete ...'; // handina
}

Rinopa pachena mugumisiro: ". Handina" Pano kukosha mashandiro JavaScript typeof = Undefined. Just kurondedzera shanduka - "kuita chinhu" harirevi. Chokwadi, kana AAA = 1, tinowana: 'Ndini', asi kana AAA = 0, zvichava saizvozvo mumutsetse wokutanga: "handina ...." Wonderful zvisingarambiki, mudzidzi wemasvomhu, uyewo nyore mugari, uye vakasagona kufunga kuti ukoshi razero ane zvakasiyana zvachose nechinangwa pane chaiyo chete. ano (atypical) zvirongwa chete anokwanisa pfungwa ushingiwo zvakadaro!

JavaScript Design typeof, uyewo mamwe akangwara mashoko kana (AAA) {... X ...} mumwe {... and ...}, ane rakaisvonaka nevatengi unhu uye zviri nyore chaizvo kushandisa.

On peculiarities pamusoro Cyrillic uye yemaarufabheti echiCyrillic neechiLatin

Professional programmer nguva dzose vanosarudza kuva Chirungu richiswedera vatambi Russian, zvechokwadi anoonga zvirongwa padariro kukura, kana zvimwe expanses cybernetics haina kuzivikanwa, asi mune dzimwe nzvimbo kombiyuta nesayenzi akaenda zvishoma nezvishoma pamukwidza. Takatanga kuwanda uye kukudziridza zvirongwa mitauro, kwakavakirwa nemarongerwo 26 earufabheti uye boka nevamwe vanhuwo zviratidzo.

Kupfuura nyore uye dzinongoitika aiva chizvarwa code, yakanga yakakwana, akakwana, asi iri zvakananga nomumwe mapurani, uye mukuru-pamwero mitauro pfungwa portability dzakachinjika architectures pakarepo dzakurumidzisa. Izvi anopesana zvikuru kuitika nguva; asi chikonzero analogue JavaScript typeof = Undefined | tambo | nhamba | boolean | kuramba | basa kana zvakanga zvisiri nyore. mitauro All vakanga tisingatauri wevakadzidza, vane yakaoma nemarongerwo uye kudzivisa nechokwadi.

Types, variables, uye kushandiswa kwawo

Point kunokosha chaizvo. Achitaipa uye rondedzero variables - rinokosha chezvinonhuwira yepurogiramu, programmer havagoni kunyora kushanda algorithm, apo haana kusangana kusiyana chaiye Data ari kuzviomesera pamutemo mufananidzo variables, arrays, zvinhu uye mabasa.

JavaScript Runoshivirira zvose vaunganidza kwemakumi emakore dzichipfekeka simba, mazano ake ose zvakakwana kuratidza kunzwisisa kuitika pamusoro nemarongerwo uye mitemo yakakodzera akaradzika semantics ake.

Mubvunzo ndewokuti, kana ichi chinofanira kuitwa kana zvakakodzera kutsanangura mhando rugwaro, JavaScript typeof basa. Chaizvoizvo noushamwari nzira kutaipa mameseji zvishoma: chimiro tambo uye nhamba. Zvisinei, basa chinyorwa chinhu anogona kutamba, uye kunyange inofa zvakagadzirwa array.join (), iro rinobatanidza ose okunze mugomba chete rugwaro, kureva, mune imwe chete mutsetse.

Banal okuti: kumativi ose pane mhando rugwaro, uye JavaScript typeof mashandiro anofanira kuva panguva yakakodzera kuita zvaaida mhando tsananguro. Izvi ichokwadi, asi tsika zvinoitika zvimwe. JavaScript typeof chinhu vachapa chete kukosha zvose zvitatu nyaya:

aaa = {}; hadde AAA = {};
= typeof ( aaa ); Res = typeof (AAA);
+= '/' + typeof window . Res + = '/' + typeof hwindo. ; gwaro;
+= '/' + typeof ( document . forms [ 0 ]); Res + = '/' + typeof (gwaro siyana [ 0]).

mugumisiro: chinhu / chinhu / chinhu

Kushandisa kunogona typeof (AAA) uye typeof AAA youduku music - hazvina zvinokosha, asi nguva dzose zviri mhinduro dzakapiwa, asi zvachose hazvirevi chinhu!

Chokwadi anova chokwadi

Zvirongwa zviri emuchina chairwo: iri kubhururuka saka kutsanya mberi kuti inofamba chikero anogara kuwedzera. Nhoroondo yacho inoenderera mberi kwemwedzi, kwemavhiki kana mazuva, dzimwe nguva kunyange maawa. The dzakananga mabasa ose simba pamusoro paumbwe imwe algorithm kuti nekugadzirisa yakadaro rokutsanya-aifamba uye vachikumbira pamusoro chamazuva kuti programmer kushanda kubva mamiriro anogona kuramba chisarudzo kuti zuva, vhiki kana kupfuura.

Natural mhinduro JavaScript typeof uye kuita chinhu vaifarira zvirongwa, izvo nemarongerwo ichi siyanei richikunda mumitauro pedyo ano, vachambokanganwa musimboti regiravhiti pamusoro chinhu. Very salient pfungwa: mutauro inova kuvaka dzine semantics, pane mamwe syntactic mitemo.

Simple date mhando havafaniri kuona kwayo mhando, kana pane kushandiswa JavaScript typeof zvakakwana. Kana zvakakodzera, kuti Runtime anotarisira zvakakodzera transformations, asi nokuda JavaScript typeof chinhu anopa mhinduro inogutsa pane chinhu uye mhando dambudziko - hanya kwake! Izvi Kufunga nokuti dzenhoroondo pfungwa pamusoro mapurogiramu zvakaoma oneka, asi mamiriro chaiyo zvinhu zvakarurama.

Care chivako - kuona kwayo mhando, kuratidza zvivako zvavo nokukuitira nzira dzavo. Zvirongwa kuti rodzai nemarongerwo wako, uye nguva yose nguva vachambokanganwa musimboti regiravhiti pamusoro nemarongerwo inoumbwa programmer semantics: kwayo gadziriro zvinhu kuti aite basa.