CSS selectors. hom selectors

, txhua tus uas koj xav kom koj muab ib lub cev nqaij daim tawv. Yuav ua li cas yuav ua rau nws? Standard CSS selectors yog tsis haum rau cov cim npe, lawv qhia tias cov tsis rau tag nrho cov blocks rau ntawm ib zaug. Cov tshuaj tsis yog yooj yim. Muab cov tub kawm. Piv txwv li, tus thawj tau txais div class = 'liab', ob - class = 'xiav', peb - class = 'ntsuab'. Tam sim no lawv muaj peev xwm yuav xaiv siv CSS ntxhuav.

Cov syntax yog raws li nram no: Qhia ib tug taw tes ( "."), Raws li los ntawm kev sau ntawv lub npe ntawm tus hauv chav kawm ntawv. Yuav kom tswj cov thawj chav tsev, siv rau kev tsim kho .red. Ob - .blue thiab thiaj li nyob.

Tseem Ceeb! Nws yog pom zoo kom siv muaj nuj nqis tseem ceeb ntawm cov chav kawm ntawv tus cwj pwm. Nws yog suav tias yog phem daim ntawv siv transliteration (eg, krasiviy-BLOK) los yog random ob peb ua ke ntawm cov tsiaj ntawv / tus xov tooj (ojfh834871). Nyob rau hauv no code, koj yuav ua txhua yam kom tau tsis meej pem, tsis hais qhov teeb meem uas yuav fim cov neeg uas yuav tsum tau koom nyob rau hauv peb tes num tom qab koj. Qhov zoo tshaj plaws kev xaiv - siv tej yam vib this, xws li BEM.

Zoo - siab kuj yooj.

Tsis zoo - lub ntau yam ntsiab tej zaum yuav yuav ib tug thiab tib yam hauv chav kawm ntawv, uas txhais tau tias lawv yuav raug kuaj ib txhij. Qhov teeb meem yog solved siv lub vib this raws li zoo raws li qub txeeg qub teg ntawm preprocessors. Nco ntsoov kom tau koj ob txhais tes tsawg, sass los yog ib txhia lwm preprocessor, lawv zoo heev piv cov ua hauj lwm.

ID selector

Hais txog qhov no version lub tswv yim coders thiab programmers yog tsis meej xwm. CSS вообще не рекомендуют использовать ID, поскольку при неаккуратном применении они могут вызвать проблемы с наследованием. Ib txhia CSS tutorials tsis pom zoo kom siv ntawm ID, vim hais tias nyob rau hauv tsis muaj tseeb daim ntawv thov lawv yuav ua rau muaj teeb meem nrog qub txeeg qub teg. Txawm li cas los, cov kws txawj yog muaj kev koom teem caij rau lawv thoob plaws hauv lub layout. Koj txiav txim siab. # »), затем имя блока. Cov syntax yog raws li nram no: lub phaus kos npe rau ( "#"), ces lub npe ntawm tus thaiv. #red. Piv txwv li, #red.

отличается от класса по нескольким параметрам. ID yog txawv los ntawm cov chav kawm ntawv nyob rau hauv ob peb txoj kev. ID. Ua ntej, cov nplooj ntawv tsis tau ob tug zoo tib ID. Lawv muab ib tug tshwj xeeb lub npe. Secondly, xws li ib tug selector muaj ib tug ntau dua ua ntej. red и укажете в таблицах CSS красный цвет фона, а затем назначите ему же id blue и укажете синий цвет, блок станет синим. Qhov no txhais tau tias yog koj qhia kom meej ib chav tsev hauv chav kawm ntawv liab thiab qhia kom meej nyob rau hauv CSS ntxhuav liab tom qab xim, thiab ces muab rau nws tib yam id xiav thiab qhia kom meej cov xim xiav, lub tsev yuav tig xiav.

Zoo - koj yuav tswj cov kev caij, uas raug nqi ntau yeej ntawm cim npe thiab kev kawm ntawv.

ID и class. Tsis zoo - yooj yim rau kom poob lawm hauv ib tug loj tus naj npawb ntawm ID thiab chav kawm ntawv.

Tseem Ceeb! ID вам, в общем-то, не нужны. Yog hais tias koj siv BEM vib this (los yog nws analogues), ID rau koj, nyob rau hauv Feem ntau, yog tsis xav tau. Cov txheej txheem no yuav siv cov layout cim cov chav kawm ntawv uas ntau npaum li cas yooj yim.

universal selector

{}. Syntax: Starlets kos npe rau ( "*") thiab kev zawm hniav, piv txwv li, {*} ...

Siv rau muab tej yam cwj pwm ib zaug tag nrho cov ntsiab ntawm cov nplooj ntawv. Thaum zoo li no muaj peev xwm yuav pab tau? box-sizing: border-box. Piv txwv li, yog tias koj xav kom koj muab cov nplooj ntawv tej khoom vaj tse box-sizing: ciam teb kem. div *{}. Yuav tsis tau tsuas yog yuav siv rau kev tswj tag nrho cov Cheebtsam ntawm cov ntaub ntawv, tab sis kuj yuav tswj tag nrho cov me nyuam ntawm cov teev thaiv, piv txwv li, div * {}.

Zoo - koj yuav tswj tau ib lub loj loj tus naj npawb ntawm cov khoom ntawm ib lub sij hawm.

Cons - tsis txaus saj zawg zog kev xaiv. Nyob rau hauv tas li ntawd, siv ntawm no selector, nyob rau hauv tej rooj plaub qeeb cov nplooj ntawv ua hauj lwm.

los ntawm tej cwj pwm uas

Ua nws tau los tswj lub caij nrog ib tug kev attribute. Piv txwv li, koj muaj ib tug xov tooj ntawm cov tswv yim cim npe nrog ib tug txawv attribute hom. Ib tug ntawm lawv - ntawv nyeem, tus thib ob - lo lus zais, peb - xov tooj. Ntawm cov hoob kawm, koj yuav teev txhua chav kawm los yog ID, tab sis nws tsis yog ib txwm yooj yim. CSS selectors ntawm cwj pwm ua rau nws tau qhia kom meej rau qhov tseem ceeb rau tej yam cim npe nrog lub siab tshaj plaws precision. Piv txwv li, zoo li no:

tswv yim [yam = 'ntawv'] {}

Qhov no selector yuav xaiv tag nrho cov cwj pwm nrog lub hom tswv yim ntawv nyeem.

Lub cuab tam yog heev saj zawg zog thiab yuav siv tau ib yam ntawm lub cim npe, nyob rau hauv uas tej zaum yuav muaj tej cwj pwm. Tab sis hais tias tsis yog tag nrho cov! Lub CSS specification muaj lub peev xwm los tswj lub ntsiab nrog txawm ntau yooj yim!

Xav txog tej yam uas koj phab muaj tswv yim nrog rau cov cwj pwm placeholder = "Sau ib lub npe" thiab cov tswv yim placeholder = "Sau lo lus zais". Lawv muaj peev xwm kuj yuav xaiv siv cov selector! Ua li no, siv cov nram qab no qauv:

tswv yim [placeholder = "Sau lub npe"] {} los yog cov tswv yim [placeholder = "Sau tus password"]

Tej zaum ntau saj zawg zog ua hauj lwm nrog tej cwj pwm. Cia hais tias koj muaj ib tug xov tooj ntawm cov cim npe nrog zoo xws li cov cwj pwm title (piv txwv li, "Caspian" thiab "Caspian"). Yuav kom xaiv ob, siv raws li nram no selections:

[Title * = "Kaspiysk"]

CSS yuav xaiv tag nrho cov khoom nyob rau hauv lub npe ntawm uas muaj tej lub cim ntawm "Caspian", piv txwv li. E., Thiab "Caspian" thiab "Caspian".

Koj yuav tau xaiv cov cim npe uas pib nrog ib tug tej cim muab:

[Title ^ = "lub cim uas koj xav tau"] {}

los yog txiav lawv:

[Title $ = "txoj cai ua cim"] {}.

Zoo - nyiaj pab ntau tshaj yooj. Koj muaj peev xwm xaiv tej uas twb muaj lawm nplooj ntsiab tsis messing nrog cov hoob.

Tsis zoo - siv kuj tsis tshua, tsuas nyob rau hauv ib rooj plaub ntug. Muaj ntau web designers xav kom vib this, txij thaum lub point chav kawm ntawv yog yooj yim dua rau kho heev heev square nkhaus thiab tej yam tshwm sim "sib npaug zos". Nyob rau hauv tas li ntawd, cov selectors tsis ua hauj lwm nyob rau hauv Internet Explorer versions 7 thiab hauv qab no. Txawm li cas los, leej twg yog tam sim no yuav tsum tau cov qub Internet Explorer?

pseudo-class selectors

Qhia ib tug pseudo-raws li txoj cai caij. Piv txwv li ,: yuj - ua li cas rau ib sab ntawm cov nplooj ntawv thaum koj yuj ,: xyuas - lub mus xyuas link. Nws kuj muaj xws li cov ntsiab xws li: ua ntej tus me nyuam thiab: kawg-tus me nyuam.

Qhov no hom ntawm selector yog nquag siv nyob rau hauv niaj hnub layout, vim hais tias ua tsaug rau nws koj yuav ua tau ib daim ntawv rau "nyob" tsis muaj kev siv ntawm JavaScript. Piv txwv li, koj xav kom paub tseeb tias thaum koj yuj dua lub khawm nrog cov chav kawm ntawv ntawm btn nws cov xim hloov. Ua li no, peb siv cov nram qab no qauv:

.btn: yuj {

tom qab-xim: liab;

}

Kev zoo nkauj yuav tsum teev nyob rau hauv qhov yooj yim thaj chaw ntawm lub khawm, txoj kev hloov tej khoom vaj tse, rau piv txwv, 0.5s - nyob rau hauv cov ntaub ntawv no, lub khawm yuav tsis ntsej mua nce ntshav instantly, thiab tsis pub dhau ib nrab ib tug thib ob.

Virtues - yog dav siv nyob rau lub "rooj txhawb siab" ntawm nplooj ntawv. Ib qho yooj yim mus use.

Tsis zoo - lawv yog cov tsis tau. Qhov no yog ib tug tiag tiag ke cuab tam. Txawm li cas los, inexperienced web designers yuav tau poob nyob rau hauv lub nplua mais ntawm pseudo-kawm ntawv. Qhov teeb meem yog solved kev kawm thiab xyaum.

pseudo-selectors

"Pseudo" - cov no yog cov chaw ntawm cov nplooj ntawv uas tsis yog nyob rau hauv HTML, tab sis lawv tseem yuav tau tswj. Koj tsis to taub? Nws yog yooj yim npaum li no mas. Piv txwv li, koj xav kom ua thawj tsab ntawv nyob rau hauv cov hlua loj thiab liab, tawm hauv lub lwm yam me me thiab dub ntawv nyeem. Ntawm cov hoob kawm, nws muaj peev xwm yuav xaus lus tias tsab ntawv nyob rau hauv ib tug ntsua kev nrog ib tug tej chav kawm ntawv, tab sis nws yog ntev thiab boring. Nws yog yooj yim npaum li mus xaiv tus tag nrho cov pawg lus thiab siv pseudo :: thawj tsab ntawv. Nws muab lub caij nyoog los tswj cov tsos ntawm thawj tsab ntawv.

Muaj ib tug loj heev tooj ntawm pseudo-hais. Sau lawv nyob rau hauv ib tsab xov xwm no tsis zoo li kawm tau ntawv zoo. Koj yuav nrhiav tau cov ntaub ntawv nyob rau hauv koj nyiam search engine.

Zoo - muab qhov yooj customize qhov zoo ntawm qhov page.

Tsis zoo - tshiab rau lawv yog feem ntau tsis meej pem. Muaj ntau selections ntawm no hom ntawm kev ua hauj lwm nkaus xwb nyob rau hauv tej yam browsers.

Yuav kom saib lub ntsab lug

Selector - ib tug haib cuab tam rau daim ntawv txaus tswj. Tsaug rau nws, koj muaj peev xwm xaiv txhua txhua ib feem ntawm cov nplooj ntawv (muaj xwb txawm cov). Nco ntsoov kawm tag nrho cov kev xaiv uas muaj, los yog txawm sau lawv cia. Qhov no yog tshwj xeeb yog ib qho tseem ceeb yog tias koj tsim complex nplooj ntawv nrog ib tug niaj hnub tsim thiab ntau ntau sib tham sib hais.