Ingxaki ephambili ngokulinganisa ixesha lokuqhutywa komsebenzi kukuba kunokuba nzima ukumisela ukuba umsebenzi othile uthatha ixesha elingakanani ukuphumeza. Oku kungenxa yokuba ixesha elithathwayo ukuze umsebenzi usebenze unokuxhomekeka kwizinto ezahlukeneyo, kubandakanywa ubungakanani kunye nobunzima bomsebenzi, ikhompyutha eqhutyelwa kuyo, kunye nesantya seprosesa yekhompyutha.
There are many ways to measure the run time of a function in JavaScript. One way is to use the Date object:
function measureFunctionRunTime(func) { var start = new Date().getTime(); func(); var end = new Date().getTime(); return end - start; }
1. Lo msebenzi uthatha iparameter ebizwa ngokuba yi "func" engumsebenzi.
2. Emva koko yenza into entsha yoMhla kwaye ifumana ixesha kwi-milliseconds (getTime()). Eli lixesha lokuqala.
3. Emva koko yenza umsebenzi owawugqithiselwe njengeparamitha.
4. Idala enye into entsha yoMhla kwaye ifumana ixesha kwakhona kwii-milliseconds (getTime ()). Eli lixesha lesiphelo.
5. Ekugqibeleni, ibuyisela umahluko phakathi kwexesha lokugqibela kunye nexesha lokuqala (ukuphela - ukuqala). Oku kukunika ixesha lokuqhuba lomsebenzi kwi-milliseconds.
Iintlobo zoManyano
Kukho iintlobo ezintathu zomanyano kwiJavaScript: engqongqo, ekhululekileyo, kwaye engacacanga.
Iimanyano ezingqongqo zezona zinemiqathango. Bavumela kuphela uhlobo olunye lwesiqalelo ukuba ludityaniswe nolunye uhlobo lwesiqalelo. Umzekelo, umanyano olungqongqo phakathi kwenani elipheleleyo kunye nomtya luyakuvumela kuphela amanani apheleleyo ukuba adityaniswe nemitya. Iimanyano ezixengayo azithinteli kangako kunemibutho engqongqo. Bavumela naziphi na iindidi ezimbini zezinto ukuba zidityaniswe, nje ukuba ukudibanisa kunengqiqo. Umzekelo, umanyano oluxekileyo phakathi kwenani elipheleleyo kunye nomtya lusenokubandakanya amanani kunye neesimboli. Iimanyano ezifihlakeleyo lolona hlobo luncinane lunemiqathango yomanyano. Bavumela naluphi na uhlobo lwesiqalelo ukuba zidityaniswe nalo naluphi na olunye uhlobo lwesiqalelo, ngaphandle kokuchaza ukuba loluphi uhlobo lomanyano. Umzekelo, umanyano olufihlakeleyo phakathi kwenani elipheleleyo kunye nomtya lungabandakanya amanani kunye neesimboli.
Typing
Ukuchwetheza kwiJavaScript kwahluke kancinane kunokuchwetheza ngezinye iilwimi. KwiJavaScript, awudingi ukuchwetheza igama elingundoqo elipheleleyo okanye igama lomsebenzi. Ungachwetheza nje unobumba wokuqala wegama elingundoqo okanye umsebenzi kwaye lonke igama liya kugqitywa ngokuzenzekelayo.
Umzekelo, ukuba ufuna ukuchwetheza "umsebenzi", ungachwetheza nje "f" kwaye iJavaScript izakugqibezela ngokuzenzekelayo lonke igama. Ukuba ubufuna ukuchwetheza "isilumkiso", ungachwetheza nje "a" kwaye iJavaScript izakugqibezela ngokuzenzekelayo lonke igama.
Chwetheza iingcebiso
Iingcebiso zochwethezo luphawu lolwimi lweJavaScript olukuvumela ukuba ukhankanye udidi lwentetho ngaphandle kokusebenzisa uhlobo lomsebenzisi. Umzekelo, le khowudi ilandelayo ichaza ukuba i-variable x linani:
var x = 5;
Unokusebenzisa iingcebiso zohlobo xa uchaza umsebenzi. Umzekelo, ikhowudi ilandelayo ichaza umsebenzi othatha igalelo iparameter yohlobo lwenombolo kwaye ibuyisela umtya:
umsebenzi wande(x) { buyisela x * x; }
