Vim li cas peb yuav tsum tau thiab yuav ua li cas sau JQuery-selector?

Niaj hnub nimno web designer yuav tsum tsis txhob tsuas txawj tsim ntawm lub HTML, lub CSS thiab JavaScript, tab sis kuj yuav tau mus ua hauj lwm nyob rau hauv lub JQuery tsev qiv ntawv, uas tsom rua lub sis ntawm JavaScript nrog HTML-cov ntaub ntawv. Hais tias nws tso cai ceev kev nkag mus rau tej lub caij Dom (daim ntawv thov programming interface uas muab kev nkag mus rau cov ntsiab lus html-cov ntaub ntawv) thiab muab rau lawv. Lub ntsiab structural units ntawm lub tsev qiv ntawv yog cov pab neeg. Nyob rau hauv thiaj li thov ib tug los yog lwm yam pab neeg, koj xav tau ib tug JQuery-selector.

Formula selectors nyob rau hauv JQuery tsev qiv ntawv

Lub selectors nyob rau hauv JQuery raws li siv nyob rau hauv CSS. Lawv yuav tsum tau xaiv cov khoom HTML-cov ntaub ntawv, siv lawv rau ua no los yog lwm txoj kev manipulating lawv (cov pab neeg). Nrhiav yog nqa tawm ntawm lub selector $ () muaj nuj nqi. Piv txwv li, $ ( 'div').

Lub selectors yuav txwv kom muab zais nyob ntawm seb cov kev xaiv ntawm hais:

• yooj yim;
• los ntawm attribute;
• lub hierarchy;
• cov ntsiab lus;
• rau qhov teeb meem no;
• kev xaiv ntawm daim ntawv teb;
• lwm leej lwm tus.

Ntsiab selectors

Nyob rau hauv 90% ntawm cov neeg thaum uas siv cov tsev qiv ntawv yog siv JQuery-selector teej tug mus rau lub ntsiab pab pawg neeg. Tag nrho cov ntawm lawv yog cov heev yooj yim thiab meej. Cia peb xav txog txhua yam uas lawv:

• * - xaiv tag nrho cov nplooj ntawv lub ntsiab, xws li lub taub hau, lub cev, thiab lwm yam.;
• p / div / sidebar / ... - xaiv tag nrho cov ntsiab hais txog lub predetermined tag (piv txwv li mus p.div, sidebar, etc ...);
• .myClass / p.myClass - xaiv lub ntsiab nrog rau cov kev cai tswjhwm chav kawm ntawv lub npe;
• # MyID / p # myID -. Xaiv tej ib yam khoom nrog rau cov muab ID.

Ntawm no yog ib qho piv txwv. Wb hais tias peb yuav tsum xaiv tag nrho cov ntsiab ntawm cov nplooj ntawv nrog par chav kawm ntawv nkag teb chaws yuav tsum yog raws li nram no: $ (par.). Yog hais tias tsim nyog xwb p ntsiab ntawm cov hoob kawm no, ces sau ntawv: $ (p.par).

tus cwj pwm selectors

Koj siv tau cov JQuery ntsiab-selector, yog hais tias peb yuav tsum xaiv ib yam khoom teej tug mus rau tej chav kawm ntawv muaj ID los yog xaiv tag nrho cov ntsiab ntawm cov nplooj ntawv. Txawm li cas los, muaj mob thaum ib yam khoom muaj tsis muaj chav kawm ntawv los yog ID. Nws yog rau qhov no thiab muaj kev xaiv los ntawm tus cwj pwm. Lawv cia koj mus ua ib tug xaiv rau ib co cwj pwm ntawm cov HTML-hais, xws li href los yog src. Qhov no attribute yog sau nyob rau hauv square nkhaus [].

Qhov yooj yim piv txwv: $ ([src]) - xaiv tag nrho cov ntsiab uas muaj src attribute. Nws yog ua tau kom nqaim tus qauv los ntawm specifying tej attribute nqi: $ ([src = 'http: // kawm ntawv / tsab xov xwm / 132222 / tus nqi']).

Koj siv tau ib co JQuery selectors hais tias koj xav kom nqaim lub tshav pob ntawm kev xaiv. Piv txwv li, $ (p [xim = xiav] [size = 12]) - yog xaiv tsuas yog cov ntsiab p, uas muaj ib tug xiav xim thiab loj 12.

selectors cov ntsiab lus

Nyob rau hauv cov ntaub ntawv uas, yog hais tias koj tsis xaiv hais raws li nyob rau hauv cwj pwm los yog yooj yim selectors, koj yuav tsum tau xa mus rau lawv cov ntsiab lus. Nyob rau hauv tag nrho muaj yog 4 selector ntawm no hom:

• : Muaj - xaiv yam khoom uas muaj cov teev ntawv nyeem;
• : Tau - xaiv hais tias muaj lwm yam hais yam ntxwv ntawm txoj kab;
• : Niam Txiv - xaiv hais tias muaj lwm yam;
• : Npliag - xaiv hais tias tsis muaj lwm yam.

Ntawm no yog ib qho piv txwv. Yuav kom xaiv tag nrho cov ntsiab div, muaj cov ntawv nyeem ntawm lub zoo, koj yuav tau sau $ (div: muaj ( 'Nyob zoo')).

selectors hierarchy

Muaj ib txoj kev rau koj xaiv hais rau JQuery, namely - raws li lawv hierarchy (uas yog, qhov ratio ntawm txhua lwm yam nyob rau HTML-page). Ib tug ntau ntawm lawv, yog li peb tuaj ob tug ntawm cov feem ntau nrov, "tus me nyuam" thiab "xeeb leej xeeb ntxwv".

Nyob rau hauv rooj plaub thawj lub ntsiab yog raug xaiv, uas yog ncaj qha xeeb leej xeeb ntxwv (cov me nyuam) ntawm ib tug muab lub caij (txwv zeej txwv koob). Piv txwv li, mus xaiv lub ntsiab ntawm daim ntawv teev nyob rau hauv lub teeb hauv chav kawm ntawv uas yog ib tug me nyuam nav daim ntawv teev, ces koj yuav tau sau: $ (ul # nav> li.light).

Qhov thib ob cov ntaub ntawv - ib tug ntau general. Muaj peev xwm yuav xaiv thiab indirect xeeb leej xeeb ntxwv ntawm lub caij. Piv txwv li, mus xaiv cov kev mus nyob rau hauv lub daim ntawv teev nav muab: $ (ul # nav a).

Yog li, nyob rau hauv JQuery ntsiab yuav tau xaiv nyob rau hauv ntau txoj kev los ntawm kev siv tsis xws li ib tug hauv chav kawm ntawv, ID, cwj pwm, cov ntsiab lus los yog qib siab ntawm HTML-daim ntawv ntsiab.