JavaScript: typeof - kokokunyanzelwa okanye ithuba

Eyayifudula uhlobo oluthile data, yaye waba nomdla imveliso yazo ukwenzela ukufumana iziphumo. Ukubusa "iingcamango Nedlac kwiinkcazo" kufika ngequbuliso, kodwa ngokwendalo. isibhengezo Pre-bume ayisekho ayisosinyanzelo kwaye ibonisa uhlobo yayo ngokubanzi ilahleko intsingiselo, ubuncinane ukuya utyando apho kuyo inxaxheba.

Umdwelisi nkqubo ulucombulule izandla zakhe, akukho mfuneko ukuvakalisa into ekuqaleni. Kudla kuphela ngexesha lokusetyenziswa iya kuba ukufumanisa ntoni ukuba, yintoni ekufanele siyenze nendlela. Ke iintlobo, bona "baye baba imilinganiselo," oko kukuthi, kuba idatha leyo ixhomekeke into!

Kuye okanye hayi, kulungile, yintoni loo nto

Inkcazo elula kakhulu "aaa 'Womendo kunye algorithm ekhoyo ukuba usetyenzwe;

aaa ; var aaa;

( aaa ) { ukuba (aaa) {
= 'I am!' Res = 'Ndim lo!' ; // I AM!
{ } Else {
= 'me no...' ; Res = 'mna no ...'; // andinayo
}

Inika isiphumo ecacileyo: ". Andiyenzi" Apha ixabiso umsebenzi JavaScript typeof = licaciswe. ukuchaza nje variable - "yokungenzi nto" njengelinye akuthethi. Kakade ke, xa aaa = 1, sifumana: 'Mna, kodwa ukuba aaa = 0, kuya kuba njani kwimeko lokuqala: "Ndiya kwenza ntoni na ...." logic nguMmangaliso, a kwezezibalo, kwakunye njengommi elula, awaba nako ukucinga ukuba zero ixabiso unentsingiselo ehlukileyo ngokupheleleyo ngaphezu kokuba umntu wokwenene. mihla (Nedlac) iinkqubo kuphela ekwaziyo iimbono unesibindi enjalo!

JavaScript Design typeof, kwakunye njengendlela ekrelekrele ukuba (aaa) {... x ...} enye {... y ...}, uneempawu yabathengi egqwesileyo kwaye Kulula kakhulu ukuyisebenzisa.

On awohluke of Cyrillic kunye nesiLatini

umdwelisi nkqubo Professional uya kusoloko bakhetha i IsiNgesi abalinganiswa ukuzoba Russian, ngokunyanisekileyo ngenxa senkqubo nokubhala.Kweli uphuhliso, xa abathile babeziindleko cybernetics ayibonwanga, kodwa nakwezinye iinkalo kwinzululwazi yekhompyutha waya ngcembe emaqhineni. Saqala ukwanda kunye nokuphuhlisa iilwimi lwenkqubo, ngokusekelwe lwesivakalisi-26 oonobumba be-alfabhethi, kunye iseti ezinye iimpawu ezifanayo.

I elula kakhulu kwaye yemvelo ikhowudi lomthonyama, bapheleliseka, igqibelele, kodwa ezithile izakhiwo ngasinye, kunye neelwimi-kwinqanaba eliphezulu ingcamango nakho ukuguqulwa kuzo lwazi bolwakhiwo lwempahla nangoko zamngxamisa. Oku okuphikisana kakhulu mzuzu yangoku: nezizathu analogu JavaScript typeof = licaciswe | string | inombolo | boolean | bengavumi | umsebenzi ukuba kwakungelula elula. Zonke iilwimi ezisesikweni ngokuthe ngqo, kufuneka ngesivakalisi engqongqo kwaye uphephe ukungaqiniseki.

Types, izinto, kwaye ukusetyenziswa kwazo

Point kubaluleke kakhulu. Typing kunye nenkcazelo yezahlukileyo - icandelo ibalulekileyo yale program, eli wenkqubo akakwazi ukubhala algorithm ukusebenza, ngoxa ukuhlangabezana ukwahlukana yokwenene i data kwi mfanekiso olungqongqo olusesikweni ezahlukeneyo, kwimiboniso, izinto kunye nemisebenzi.

JavaScript Luthwala iinto zonke accumulated ngaphezu kwamashumi amandla asebenzayo, yonke yoyilo zakhe zibonisa ngokupheleleyo ukuqonda yangoku lwesivakalisi kunye nemithetho efanelekileyo babekwa semantics zakhe.

Umbuzo kukuba, xa oku kufuneka kwenziwe xa kuyimfuneko ukuchaza uhlobo lombhalo, JavaScript typeof msebenzi. Eneneni iindlela uhlobo lwetekisi kancinane: i Umtya womsebnzi kunye nenombolo. Nangona kunjalo, indima kwento itekisi ebetha, yaye kukho uluhlu lwe array.join yoyilo (), edityaniswe zonke izinto zibe itekisi enye, oko kukuthi, emgceni omnye.

mazwi Banal: ngeenxa zonke kukho uhlobo lombhalo kunye JavaScript typeof msebenzi kufuneka zibe ngexesha elifanelekileyo ukwenza uhlobo ingcaciso oyifunayo. Oku kuyinyaniso, kodwa kusenziwa kuvela ngenye indlela. JavaScript typeof into aya kukunika ixabiso efanayo kuzo zonke zontathu ezi meko:

aaa = {}; var aaa = {};
= typeof ( aaa ); Res = typeof (aaa);
+= '/' + typeof window . Res + = '/' + typeof window. ; uxwebhu;
+= '/' + typeof ( document . forms [ 0 ]); Res + = '/' + typeof (iifom uxwebhu [ 0]).

japan: into / into / into

Ukusebenzisa kungenziwa typeof (aaa) kunye nefomathi typeof aaa umculo - akuyomfuneko, kodwa zonke iimeko impendulo unikwa, kodwa ngokupheleleyo akuthethi nto!

Ukungaqiniseki uba ngokuqiniseka

Lwenkqubo iimpawu nemiba abayinqobo, ukuba uhamba ngokukhawuleza phambili ukuba isikali motion esoloko ukwandisa. Le ngxelo iqhubeka iinyanga, iiveki okanye iintsuku, maxa wambi nkqu iiyure. Imisebenzi ethile malunga nemiba ye ukuyilwa algorithm ukuxazulula enjalo ingaba kukuzila ngokukhawuleza kwaye befuna phezu ekuqhubekekeni ukuba wenkqubo wokusetyenzwa urhulumente ukwala isigqibo ngosuku, ngeveki okanye ngaphezulu.

isisombululo Natural JavaScript typeof nokuqhele ukwenziwa into ebomini iinkqubo, nto leyo kule lwesivakalisi yahluke kancinane egqubayo iilwimi ezimelene mihla, ngokutshintsha kumbindi womxhuzulane kwi into. ngongoma eqalise kakhulu: ulwimi uba kokuyilwayo equka semantics, kunokuba uluhlu lwemithetho syntactic.

Iintlobo Simple data Akuyomfuneko ukugqiba udidi yayo, okanye mandithi ukusetyenziswa JavaScript typeof ngokwaneleyo. Ukuba kuyimfuneko, eli sokusebenza ithatha unonophelo na utshintshwano ezifanelekileyo, kodwa ngenxa JavaScript typeof into inika eyona mpendulo enengqondo injongosenzi kunye nohlobo ingxaki - ukukhathazeka kwakhe! Le logic iingcamango classical malunga nodweliso lwenkqubo nzima perceptible, kodwa imeko yokwenene izinto tye.

Care iziko - ukugqiba udidi yayo, ukubonisa iimpawu zabo baze benze iindlela zabo. Zokuhlela khazimlisani kwezivakalisi yakho, uze mzuzu zonke ixesha ngokutshintsha kumbindi nondiliseko lwesivakalisi lisekwa semantics umdwelisi nkqubo: inkqubo yalo yezinto enze umsebenzi.