Kutheni Kufuneka thina ukuba kurekhodwe ukuba JQuery-umkhethi?

Modern mqambi web akufuneki kuphela bagqwese iziseko le HTML, le CSS kunye JavaScript, kodwa babe nako ukusebenza kwithala leencwadi JQuery, elijolise impefumlelwano JavaScript nge HTML-amaxwebhu. Ukuba ivumela unikezelo olukhawulezayo kuzo naziphi element DOM (isinxulumanisi senkqubo yekhompyutha olunika unikezelo kwi iifayile-html umxholo) kunye zokuzisebenzisa. Iiyunithi eziphambili noshowo kwithala leencwadi ke qela. Ukuze isicelo elinye okanye elinye iqela, udinga JQuery-umkhethi.

selectors Formula kwithala JQuery

Le selectors e JQuery ngokusekelwe isentyenziselwe CSS. Kuyafuneka ukuba ukhethe izinto HTML-ifayile, ukuba usebenzise ngokubacandisa ezi okanye ezinye iindlela zokwenza them (team). Ukufuna lwenziwa nge umkhethi $ () umsebenzi. Umzekelo, $ ( 'div').

Le selectors nga zihlelwe kuxhomekeke kwindlela ukhetho lweziqalelo:

• esisiseko;
• yi lophawu;
• sabaphathi;
• isiqulatho;
• kwi le meko;
• Ukukhetha zefom;
• abanye.

selectors key

Ngowe-90% amatyala xa usebenzisa le layibrari isetyenziswa JQuery-yokukhetha ngoweqela engundoqo. Bonke bephela kakhulu ilula kwaye icacile. Makhe siqwalasele ngamnye kubo:

• * - ikhetha zonke izinto page, kuquka intloko, umzimba, etc;.
• p / div / esecaleni / ... - kukhetha konke imiba ephathelele ithegi kwangaphambili (ithetha ukuba p.div, esecaleni, etc ...);
• .myClass / p.myClass - ikhetha iziqalelo kunye igama elichaziweyo iklasi;
• # MyID / p # myID -. Ikhetha nayiphi na into omnye ID elinikiweyo.

Nanku umzekelo. Masithi kufuneka ukhethe zonke izinto kwiphepha kunye yokungena eklasini par iza kuba ngolu hlobo lulandelayo: (. Kumhlathi) $. Ukuba kuyimfuneko kuphela elements p kule klasi, uze ubhale: $ (p.par).

nokuchazwa selectors

Uyakwazi ukusebenzisa JQuery engundoqo-yokukhetha, xa kufuneka ukhethe into eyeyomnye ukuba ID udidi okanye khetha zonke izinto kwi-page. Nangona kunjalo, kukho iimeko xa nto akukho iklasi okanye ID. Kungenxa yale kwaye kukho ukhetho yi ngemfanelo. Amvumela ukuba wenze ukhetho kwi ethile attribute ye HTML-elements, ezifana href okanye src. Le lesiphumo ibhalwe kwizibiyeli ezisisikwere [].

Umzekelo elula: $ ([src]) - ikhetha zonke izinto zibe src ngemfanelo. Kuyenzeka ukuba unciphise isampulu ngokukhankanya ixabiso ethile sophawu: $ ([src = 'http: // site / inqaku / 132222 / ixabiso']).

Ungasebenzisa ezinye selectors JQuery ukuba ufuna ukuvala intsimi oyikhethileyo. Umzekelo, $ (p [umbala = oluhlaza] [ubukhulu = 12]) - mazikhethwe kuphela ezo zinto p, leyo kufuneka umbala oluhlaza kunye nobukhulu 12.

Umxholo Selectors

Kwimeko enjalo, ukuba akukwazi ukhethe izinto ezisekelwe iimpawu okanye selectors esisiseko, kufuneka ujonge ikuquletheyo. Xa lilonke kukho 4 yokukhetha yolu didi:

• : Iqulethe - ukhetha izinto eziqulathe umbhalo elichaziweyo;
• : Ingaba - ukhetha izinto eziqulathe nezinye izinto uphawu umgca;
• : Abazali - ukhetha izinto eziqulathe nayiphi na enye;
• : Empty - ukhetha izinto musa ayiqulathanga naluphi na.

Nanku umzekelo. Ukukhetha zonke izinto div, equlethe kwisicatshulwa Hello, kufuneka ubhale $ (div: iqulethe ( 'Hello')).

Selectors sabaphathi

Kukho nenye indlela ukukhetha izinto e JQuery, oko kukuthi - ngohlobo lwemigangatho yabo (oko kukuthi, umlinganiselo omnye komnye kwi-HTML-page). A lot of kubo, ngoko asondeze ezimbini ethandwa, "umntwana" yaye "ka".

Kwimeko yokuqala izinto ezikhethiweyo, siyinzala ngqo (abantwana) of a element elinikiweyo (amadlozi). Umzekelo, ukuba ukukhetha iziqalelo uluhlu eklasini kukhanya uluhlu nav umntwana, ngoko ke kufuneka ukuba ubhale: $ (ul # nav> li.light).

Ityala lesibini - a jikelele ngakumbi. Kukho kungaba ukhethe kunye nenzala obungangqalanga element. Umzekelo, ukuba ukhethe amakhonkco ngaphakathi kuluhlu nav ukumisela: $ (ul # nav a).

Ngenxa yoko, e JQuery izinto kungaba ukhethe ngeendlela ezahlukeneyo ngokusebenzisa iparameters ezifana iklasi, ID, iimpawu, umxholo okanye uluhlu lweziqalelo HTML-uxwebhu.