Yini amaSpredishithi wesitayela se-Cascading?
Amawebhusayithi anenqwaba yezicucu, kufaka phakathi izithombe, umbhalo, kanye nemibhalo ehlukahlukene. Lezi zincwadi azibandakanyi kuphela ezingase zixhunywe kusuka kumakhasi ahlukahlukene, afana namafayela e-PDF, kodwa futhi amadokhumenti asetshenziselwa ukwakha amakhasi ngokwawo, njengemibhalo ye-HTML yokunquma isakhiwo sekhasi kanye ne-CSS (Cascading Style Sheet) amadokhumenti ukuphoqa ukubukeka kwekhasi. Lesi sihloko sizocwaninga ku-CSS, sihlanganisa nokuthi siyini nokuthi sisetshenziselwa kumawebhusayithi namuhla.
Isifundo somlando we-CSS
I-CSS yaqala ukuthuthukiswa ngo-1997 njengendlela yabathuthukisi bewebhu ukuchaza ukubukeka kwamakhasi ewebhu abakudala. Kwakuhloswe ukuvumela ochwepheshe bewebhu ukuthi bahlukanise okuqukethwe nokuhlelwa kwekhodi yewebhusayithi kusuka ekuklanyweni okubukwayo, into engakaze ibe khona ngaphambi kwalesi sikhathi.
Ukuhlukaniswa kwesakhiwo nesitayela kuvumela i-HTML ukwenza umsebenzi owengeziwe owawusekelwe ekuqaleni - umaketha wokuqukethwe, ngaphandle kokukhathazeka ngokuklama nokuhlelwa kwekhasi ngokwalo, into eyaziwa ngokuthi "ukubukeka nokuzizwa" kwekhasi.
I-CSS ayitholanga ekuthandweni kuze kube ngu-2000, lapho iziphequluli zewebhu ziqala ukusebenzisa okungaphezulu kwefonti eyisisekelo kanye nezici zombala zalolu limi lomlingo. Namuhla, zonke iziphequluli zanamuhla zisekela zonke i-CSS Level 1, iningi lezinga le-CSS 2, ngisho nezici eziningi ze-CSS Level 3. Njengoba i-CSS iqhubeka nokuguquka futhi izitayela ezintsha ziqaliswa, iziphequluli zewebhu ziqale ukusebenzisa amamojula athola ukusekelwa okusha kwe-CSS kulawo maphepheli futhi unikeza abakhi bewebhu amathuluzi anamandla amasha wokusebenza.
Eminyakeni eminingi (edlule), bebakhethe abakhiqizi bewebhu abenqaba ukusebenzisa i-CSS ekuklanyeni nasekuthuthukiseni kwamasayithi, kodwa lo mkhuba uvele ngaphandle komkhakha namhlanje. I-CSS manje iyinqubo ejwayelekile kakhulu ekusetshenzisweni kwewebhu futhi uzobe ucindezelwe kanzima ukuthola noma ubani osebenza embonini namuhla ongenawo okungenani ukuqonda okuyisisekelo kwalolu limi.
I-CSS yi-Abasebenzisi
Njengoba sekushiwo kakade, igama elithi CSS lisho "I-Cascading Style Sheet." Ake siphule le nkulumo kancane ukuze uchaze ngokugcwele ukuthi la maxwebhu akwenzani.
Igama elithi "ishidi lesitayela" lisho idokhumenti ngokwalo (njenge HTML, amafayela e-CSS asuke nje amadokhumenti wombhalo angalungiswa ngezinhlelo ezihlukahlukene). Amashidi wesitayela asetshenziselwe ukuklanywa kwedokhumenti iminyaka eminingi. Ziyizinto ezicacisiwe zobuchwepheshe be-layout, kungaba ukunyathelisa noma ukuxhumeka ku-intanethi. Abadicileli bephrinta basebenzise amashidi wesitayela eside ukuze baqiniseke ukuthi imiklamo yabo ishicilelwe ngqo ekuchazeni kwabo. Ishidi lesitayela sekhasi lewebhu linomgomo ofanayo, kodwa ngokusebenza okungeziwe kokutshela isiphequluli sewebhu ukuthi singanikeza idokhumenti ibhekwe. Namuhla, amashidi wesitayela se-CSS angasebenzisa futhi imibuzo yemidiya ukushintsha indlela ikhasi elibukeka ngayo amadivayisi ahlukene namasayizi weskrini . Lokhu kubaluleke kakhulu ngoba kuvumela ukuthi idokhumenti eyodwa ye-HTML ingenziwa ngokuhlukile ngokuya kwesikrini esetshenziselwa ukuyifinyelela.
I-cascade iyinxenye ekhethekile ngempela yegama elithi "isitayela sesitayela se-cascading". Ishidi lesitayela sewebhu lenzelwe ukuhambisa uchungechunge lwezitayela kulowo shici, njengomfula phezu kwemvula. Amanzi emfuleni ahlasela wonke amatshe emanzini, kodwa kuphela ezansi ezithinta ngqo lapho amanzi azogeleza khona. Kanjalo okufanayo ne-cascade kumawebhusayithi wesitayela sewebhu.
Njalo ikhasi lewebhu lithinteka okungenani ishidi lesitayela esisodwa, noma ngabe umklami wewebhu akasebenzisi izitayela. Leli shidi lesitayela yishidi lesitayela se -agent yomsebenzisi - eyaziwa nangokuthi izitayela ezizenzakalelayo ezizosetshenziswa isiphequluli sewebhu ukubonisa ikhasi uma kungekho eminye imiyalo enikeziwe. Isibonelo, ngama-hyperlink okuzenzakalelayo aqoshiwe nge-blue futhi agcizelelwe. Lezo zitayela zivela kushidi lesitayela sesiphequluli esizenzakalelayo. Uma umklami wewebhu ehlinzeka ngeminye imiyalelo, noma kunjalo, isiphequluli sidinga ukwazi ukuthi yimiphi imiyalo enokuqala. Zonke iziphequluli zinezindlela zokuzenzakalelayo zazo, kodwa eziningi zazo (okufana nezixhumanisi zombhalo ogqamile) zabiwe kuwo wonke ama-browser noma izinguqulo ezinkulu.
Ngesinye isibonelo sesiphequluli esingalungile, kusiphequluli sami sewebhu, ifonti ezenzakalelayo i-" Times New Roman " iboniswe ngosayizi 16. Cishe akukho namakhasi engiwavakashelayo abonisa kulowo mndeni wefonti nosayizi, noma kunjalo. Lokhu kungenxa yokuthi i-cascade ichaza ukuthi amashidi wesitayela sesibili, asetshenziswe ngabaqambi ngokwabo, ukuhlenga kabusha usayizi wefonti nomndeni, ngaphezu kwezinguquko zesiphequluli sami sewebhu. Noma yimaphi amashidi wesitayela owakhayo wekhasi lewebhu azoba nokucacile okwedlula izitayela ezizenzakalelayo zesiphequluli, ngakho-ke lokho okuzenzakalelayo kuzosebenza kuphela uma ishidi lakho lesitayela lingabanqobeli. Uma ufuna izixhumanisi zibe ziluhlaza okwesibhakabhaka futhi zikhonjiswe, akudingeki wenze lutho kusukela lokho okuzenzakalelayo, kodwa uma ifayela le-CSS lakho lesayithi lithi izixhumanisi kufanele zibe luhlaza, lo mbala uzokwandisa ukuluhlaza okuzenzakalelayo. I-underline izohlala kule sibonelo, ngoba awuzange ucacise ngenye indlela.
Uphi i-CSS esetshenziswayo?
I-CSS ingasetshenziselwa ukuchaza ukuthi amakhasi ewebhu kufanele abheke kanjani uma ebhekwa kwamanye abezindaba ngaphandle kwesiphequluli sewebhu. Isibonelo, ungakha ishidi lesitayela sokuphrinta elizochaza ukuthi ikhasi lewebhu kufanele liphrintiwe kanjani. Ngoba izinto zekhasi lewebhu ezinjengezinkinobho zokuhamba noma amafomu ewebhu angeke abe nenjongo ekhasini eliphrintiwe, Ishidi Lokushicilela Lingasetshenziswa "ukuvala" lezo zindawo lapho ikhasi liphrintiwe. Ngenkathi kungewona umkhuba ovamile kumasayithi amaningi, ukhetho lokudala amashidi wesitayela sokuphrinta lunamandla futhi lukhangayo (kulwazi lwami - abalingani abaningi bewebhu abenzi lokhu ngoba nje isabelo sebhajethi singasabi ukuthi lo msebenzi owengeziwe wenziwe ).
Kungani CSS Kubalulekile?
I-CSS ingenye yamathuluzi anamandla kakhulu umklami wewebhu ongafunda ngoba nalo ungathinta konke ukubukeka kwewebhusayithi. Amashidi wesitayela aqoshiwe angahle abuyekezwe masinyane futhi avumele amasayithi ukuthi ashintshe okubalulekile okubonakalayo esibukweni, okubonisa ukuthi kubalulekile futhi kugxile kuzivakashi, ngaphandle kokushintshwa okudingeka kwenziwe emakhasini we-HTML angaphansi.
Inselelo enkulu ye-CSS yukuthi kuncane kakhulu okumele ifunde - kanti neziphequluli ezishintsha nsuku zonke, lokho okusebenza kahle namuhla kungase kungabi nengqondo kusasa njengoba izitayela ezintsha zisekelwa futhi abanye behlehliswa noma bangabikho ngenxa yesizathu esisodwa noma esinye .
Ngenxa yokuthi i-CSS ingahle ihlanganise futhi ihlolisise ukuthi iziphequluli ezihlukene zingachaza kanjani futhi zisebenzise lezi ziqondiso ngokuhlukile, i-CSS ingaba nzima kunokuba i-HTML ecacile ikwazi ukuqonda. I-CSS iphinda ishintshe kuziphequluli ngendlela i-HTML engenzi ngayo. Uma usuqala ukusebenzisa i-CSS, noma kunjalo, uzobona ukuthi ukuhlanganisa amandla amashidi wesitayela kuzokunika ukuguquguquka okungaqondakali endleleni obeka ngayo amakhasi wewebhu futhi uchaza ukubukeka kwawo nokuzizwa. Ngandlela-thile, uzozihlanganisa "isikhwama sezintambo" zezitayela nezindlela ezikusebenzele esikhathini esidlule nokuthi ungabuyela nini njengoba usakha amaphuzu ewebhu amasha esikhathini esizayo.
Isihloko sokuqala sikaJennifer Krynin. Ehlelwe nguJeremy Girard ngo-7/5/17,