Kungani sidinga nendlela ukuqopha jQuery-isikhethi?

sewebhu umklami Modern akufanele kuphela balukhulume izisekelo-HTML, CSS futhi i-JavaScript, kodwa futhi ukwazi ukusebenza umtapo jQuery, egxile nokuxhumana JavaScript nge-HTML imibhalo. Lokho kuvumela ukufinyelela okusheshayo kunoma isici se-DOM (isikhombi sokuhlela ukusebenza enikeza ukufinyelela okuqukethwe kwe-html-amafayela) kanye nekucinisa kubo. The main amayunithi isakhi umtapo kukhona iqembu. Ukuze usebenzise noma elinye iqembu, udinga jQuery-isikhethi.

Formula kubakhethi emtapweni jQuery

I kubakhethi e jQuery ekusebenziseni ku-CSS. Basuke edingekayo ukuze ukhethe izinto HTML-ifayela, ukuzisebenzisa ukuze abangele lezi noma ezinye izindlela lokusebenzisa izindlela zokwenza kwabo (iqembu). Ukucinga wenziwa nge isikhethi $ () umsebenzi. Ngokwesibonelo, $ ( 'div').

I kubakhethi kungenziwa labizwa kuye indlela ukukhethwa izakhi:

• eziyisisekelo;
• by ngemfanelo;
• sabaphathi;
• okuqukethwe;
• isimo;
• kukhethwa ifomu kanye namasimu asemaphandleni;
• abanye.

kubakhethi Key

Ngo-90% amacala uma usebenzisa lo mtapo wolwazi isetshenziswa jQuery-isikhethi bohlanga main. Bonke bangabangasokile ngempela elula futhi ecacile. Ake sicabangele ngayinye yalezi zinkulumo:

• * - ukhetha zonke izakhi khasi, kuhlanganise ikhanda, umzimba, njll.
• p / div / eseceleni / ... - ukhetha zonke izakhi ephathelene ithegi predetermined (okusho ukuthi p.div, indawo eseceleni, njll ...);
• .myClass / p.myClass - ukukhethela izakhi enegama ekilasini esibekiwe;
• # MyID / p # myID -. Ikhetha iyiphi into eyodwa ene-ID enikeziwe.

Nasi isibonelo. Ake sithi kudingeka ukhethe zonke izakhi ekhasini par ekilasini entry kuyoba kanje: (. Par) $. Uma kudingekile kuphela p tincenye ekilasini, bese ubhala: $ (p.par).

attribute kubakhethi

Ungasebenzisa jQuery main-isikhethi, uma kudingeka ukhethe into nakunoma yisiphi isigaba ID kokuba noma khetha zonke izakhi ekhasini. Nokho, zikhona izimo lapho into ayinaso isigaba noma i-ID. Kungenxa yalesi futhi kukhona okukhethiwe by ngemfanelo. Bavumela ukuba wenze ukukhetha kwezinye imfanelo-HTML-izakhi, ezifana href noma src. Lesi sibaluli okulotshwe kubakaki [].

Isibonelo elula: $ ([src]) - ukhetha zonke izakhi ukuthi babe src ngemfanelo. Kungenzeka ukuba unciphise isampula ngokucacisa ezithile ngemfanelo Inani: $ ([src = 'http: // site / sihloko / 132222 / Inani']).

Ungasebenzisa amanye kubakhethi jQuery uma ufuna unciphise ensimini lokuzikhethela. Ngokwesibonelo, $ (p [color = blue] [size = 12]) - akhethiwe labo kuphela izakhi p, okuyinto abe nombala oluhlaza kanye nosayizi 12.

kubakhethi okuqukethwe

Kuleso simo, uma awukwazi ukukhetha izakhi okusekelwe izimfanelo noma kubakhethi eziyisisekelo, kufanele ubheke okuqukethwe kwabo. Sekukonke kukhona 4 isikhethi yalolu hlobo:

• : Iqukethe - ukhetha izinto eziqukethe umbhalo okhethiwe;
• : Ingabe - ukhetha izakhi eziqukethe ezinye izici sici umugqa;
• : Umzali - ukhetha izakhi eziqukethe yimuphi omunye;
• : Empty - ukhetha izakhi ukuthi awanalo iyiphi enye.

Nasi isibonelo. Ukukhetha zonke izakhi div, eliqukethe umbhalo Sawubona, udinga ukubhala $ (div: kuhlala tindzawo ( 'Sawubona')).

kubakhethi wokwehlayo

Kukhona enye indlela esingathola ukukhetha izakhi Jquery, okungukuthi - ngokuvumelana wokwehlayo yabo (okungukuthi, isilinganiso nomunye ku-HTML ekhasini-). Iningi labo, ngakho sethula emibili ethandwa kakhulu, "ingane" futhi "ozalweni".

Esimweni sokuqala izici ezikhethiwe, okuyinto siyinzalo oqondile (babantwana) zika-elementi okunikeziwe (amadlozi). Ngokwesibonelo, ukuze ukhethe izakhi ohlwini eklasini ukukhanya okuyinto uhlu ingane nav ke kudingeka ukuba abhale: $ (ul # nav> li.light).

Eyesibili icala - ejwayelekile ngaphezulu. Kukhona kungenziwa kukhethwe nenzalo ongaqondile element. Ngokwesibonelo, ukuze ukhethe izixhumanisi ngaphakathi uhlu nav linqume: $ (ul # nav a).

Ngakho, ngo-jQuery izakhi kungenziwa kukhethwe ngezindlela ezihlukahlukene ngokusebenzisa nemingcele ezifana isigaba, i-ID, izimfanelo, okuqukethwe noma isigaba sabefundisi izakhi-HTML dokhumenti.