I-JavaScript: cima ityala - khetha okukhethwa kukho

Isizathu sisoloko sisinye, ixabiso lingaba likhulu. Okanye mhlawumbi ngenye indlela ngeenxa zonke: kubaluleka omnye kuya kuba nezizathu ezininzi zokubonakala kwayo. Kukho nawuphi na, kuyimfuneko ukuthatha isigqibo esisodwa kuxhomekeke kwimeko ethile, okanye ngokulandelelana.

Nangona isisombululo sinokuzikhethela ezininzi, indlela enye kuphela iya kukhokelela kunoma yiphina injongo, kodwa ngokuqhelekileyo kukho iindlela ezininzi, kwaye omnye kufuneka enze ukhetho.

Ingxelo yenkcazo yeklasi xa (imeko) {algorithm 1 ukuba imeko yinyani} enye {algorithm 2 ukuba imeko iphosakeleyo} inika kuphela ukhetho olubini. Kodwa nangona umsebenzi ongokoqobo uhlala unika iinketho ezininzi.

Ilula "ayikho", kodwa enye imeko

Ukwakhiwa kweJavaScript, itshintsho = imeko ezininzi zeemeko. Inye efanayo ingafumaneka ngokusebenzisa idibaniselwano ye-If statement. Nangona kunjalo, ngokungathandabuzekiyo, ukuhluka kokuqala kudibeneyo kunye nokwenza ngokufanelekileyo. Ukongezelela, ngokusemthethweni isigqibo kwisibini sesibini siya kufuna umthuthukisi wezakhono ezinkulu.

Nantsi inhlanganisela ukuba (...) {...} enye {...} kwaye uzame {...} inkathazo (...) {...} inikezela ukuqala kwenkqubo yokutshintshwa kwe-AJAX kwi-algorithm. Impendulo iqhutyelwa kwisitethi esifanayo semeko.

Inkcazo yokuguqula iJavaScript: umzekelo

Uhlobo oluphambili lwangaphandle phakathi kokukhethwa kwenketho kunye nemeko eyodwa: awukwazi ukubhala ezimbini kodwa iibhloko zokulawula eziliqela. Kuphela kuphela okanye embalwa kuphela eya kwenziwa.

I-J avaScript switch case ikuvumela ukuba unikezele izilungiso ezininzi, kuxhomekeke kwixabiso lexabiso okanye ixabiso lentetho. Kubalulekile ukuqwalasela ukuba ukhetho lwe-algorithm olufunwayo luya kwenziwa ngumdlalo ochanekileyo wexabiso le-switch () kunye nexabiso elichazwe kwimeko. Isimboli "1" kunye nenani 1 alifani, uhlobo lokuguqulwa lucatshulwa alusebenzi apha.

Ukusebenzisa Amacandelo amaninzi

Isici esichaphazelekayo sokhetho kwi-J avaScript yecala lokushiya ukungabikho kweebhanki zebhloko - {...}, eziza kubelwa kuphela ukuqala nokuphela komzimba walo mqhubi. Icandelo ngalinye lecala lipheliswa yintetho yekhefu, engenakho.

Kule mizekelo, ikhefu lanyuka kwiqendu lokuqala. Utshintsho olusekhohlo luya kunika umphumo we-Variant2, kuba ngokuqinisekileyo uza kuqaliswa njani, kwaye ngokuhlukileyo ngakwesokudla i-Variant1Variant2 iya kufunyanwa, ekubeni iyokuqala iya kwenziwa, kodwa ayiyi kuba nempembelelo kwimeko yesibili, kwaye ngaphandle koko, abaqhubi becandelo lokuqala abayi kuphazamisa, ngoko Okwesibini: phakathi kwabo akukho mpazamo yekhefu, kwaye kabini ityala lokutshintshwa kweJavaScript alikho. Kufuneka kuqatshelwe ukuba ukutshintsha i-variable iCond kwisakhiwo somzimba akuyi kuba nemiphumo.

Ukunyaniseka kwekhowudi kunye nenyaniso yengxaki

I-JavaScript yilwimi oluhle, ngokukhawuleza, ngokukhawuleza, nge-syntax ehambelana kakuhle. Icala lokutshintsha i- JavaScript lisebenza kakuhle, likuvumela ukuba uchaze ngokucacileyo kwaye uchane ngokucacileyo uhlobo olukhethiweyo lwezikhetho kwiimeko ezithile.

Abasebenzisi bokukhetha bangeniswa omnye komnye. Kwimacandelo abo, ityala linokubhaliweyo kweengxelo, izitshixo, naziphi na ezinye ezakhayo. Musa ukungahoywa ubuninzi bezinto eziguqukayo. Ukusetyenziswa kuyo yonke indawo kufuneka kuchazwe jikelele.

Nangona kunjalo, akufanele usebenzise kakubi iJavaScript. Inkqubo yokutshintsha iyisisombululo esihle kakhulu se-branching, kodwa ayihambanga ngexabiso elikhulu lekhowudi. Ngaphezu kokucingisisa kunye nokusebenza okukhethiweyo okukhethiweyo kwenziwa, kunzima ngakumbi ukutshintsha kamva.

Umsebenzi wangempela awuzange ume, kwaye ukuba asiyikuqwalasela utshintsho kwinkqubo yokuyixazulula, ke ukususela kumzuzwana wokugqitywa komsebenzi, kwiintsuku zokuqala zokusebenza kwezixhobo ezidalwe, ukungalungi kunye nokusilela kuya kubonakala. Lo msebenzi uya kuqhubela phambili, kwaye isayithi iya kupheliswa.

Kulo mbono, inkalo enkulu yecala lokutshintsha iJavaScript livela kubukhulu bayo kunye nobunzima. Ukuba awusebenzisi kakubi le nto, unokufezekisa impumelelo eyenziwe ngokukhetha kunye nokuncinci.

Isimo + Isixazululo = ukujika kwintshukumo entsha

Ingxaki ehlelwe ngokuchanekileyo isisombululo. Nangona umsebenzi, ngokucacileyo, ngokwawo awukwazi ukunquma nantoni na ukuyifutshane.

Le meko isetyenziswe yonke indawo (umsebenzi omncinci wancinci). Ukuphunyezwa kwimeko = ukusetyenziswa kwekhowudi ethile. Ukusebenzisa iJavaScript kwimeko yokutshintshela kubini inkokhelo yokufashisa kunye nesimo esibalulekileyo. Oku kwenziwa kuzo zonke iilwimi, kuba kulula kwaye zilungele.

Emva kokuzalwa "uLisp" kunye ne "Prologue", iilwimi ezifanayo zolimi. Kukho iimfazwe malunga nabaqhubi beenguqu kunye neelayibhile. Uzame ukulinganisa okufanelekileyo kwindlela yokusebenza yokubhala inkqubo. Namhlanje, umqhubi omkhulu unomdla ngokukhuthaza izinto ezijoliswe kuyo.

Nangona kunjalo, kude kube ngoku kwimisebenzi yomsebenzi yanamhlanje ifumana ixabiso layo elibalulekileyo. Kodwa iinjongo zeengcamango zanamhlanje zichanekileyo ukuba izinto ngokwazo zibeka iimeko kwaye zifumene izicombululo. Emva koko, into yinto yokuqokelela i-syntax kunye ne-semantics.