JavaScript Arrays : He mahara ki te whakaiti i te mahi

Tukuna ki runga e

wetereo

arr.reduce(callbackFunction, [initialValue])

Aha e whakaiti mahi?

Whakaititia Ko te mahi e koropiko i roto i te ngohi.

Ka taea te whakamana Operations i runga i te ngohi mā te mahi hokiwaea.

I te mutunga o nga ngā mahi i runga i te ngohi, whakaiti hoki i te uara kotahi

Whakaititia taea te whakamahi, hei tauira, ki te tapeke i te kata hokohoko

tauira

  kia faanahohia = [1,2,3,4,5];
  arr.reduce( (accumulator, currentValue, currentIndex, ngohi) => { 
      //te tahi mau ngā mahi;
      hoki te tahi mea;
  });

 

Ko te Taumahi Hokiwaea

whakahuatia te mahi hokiwaea te hoki ia huānga i roto i te ngohi, haere i roto i 4 tohenga e haere i roto i te taha o te pānga whakaiti.

enei 4 tohenga ka taea te whakamahi i roto i to tatou mahi hokiwaea.

E wha tohenga

  1. accumulator – Ko te huānga tuatahi o te ngohi i runga i te koropiko tuatahi uara tuatahi ranei, ki te tukua. Katahi te uara hoki o te koropiko o mua.
  2. currentValue – Te huānga o nāianei i roto i te ngohi. Tīmata i te huānga tuarua i roto i te ie ngohi. faanahohia[1], ka kore e haere te tautohe uara tuatahi. tīmata Ki te haere te tautohe uara tuatahi te uara ka nāianei i te huānga 1 i roto i te faanahohia ngohi[0].
  3. currentIndex – Ko te taupū o te huānga o nāianei.
  4. ngohi – Ko te ngohi katoa.

tauira mahi

kia faanahohia = [1,2,3,4,5];

arr.reduce(
  (accumulator, currentValue, currentIndex, ngohi) => {
    console.log(`accumulator (I te koromeke 1, accumulator he faanahohia[0], na ko reira te uara hoki o te koropiko o mua): ${accumulator}`);
    console.log(`currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[1]): ${currentValue}`);
    console.log(`currentIndex: ${currentIndex}`);
    console.log(`ngohi: ${ngohi}`);
    console.log('---');
    accumulator hoki + currentValue;
  }
);

huaputa

accumulator (I te koromeke 1, accumulator he faanahohia[0], na ko reira te uara hoki o te koropiko o mua): 1
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[1]): 2
currentIndex: 1
ngohi: 1,2,3,4,5
---
accumulator (I te koromeke 1, accumulator he faanahohia[0], na ko reira te uara hoki o te koropiko o mua): 3
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[1]): 3
currentIndex: 2
ngohi: 1,2,3,4,5
---
accumulator (I te koromeke 1, accumulator he faanahohia[0], na ko reira te uara hoki o te koropiko o mua): 6
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[1]): 4
currentIndex: 3
ngohi: 1,2,3,4,5
---
accumulator (I te koromeke 1, accumulator he faanahohia[0], na ko reira te uara hoki o te koropiko o mua): 10
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[1]): 5
currentIndex: 4
ngohi: 1,2,3,4,5
---

 

Whakarato i te uara tuatahi

Te tauwhāiti tuarua te tawhā (initialValue) i roto i te mahi whakaiti ka meinga initialValue ki kia haere i roto i rite te tohenga accumulator i runga i te koru tuatahi.

Kia mōhio e te uara o nāianei i runga i te koropiko 1 inaianei tīmata i te huānga tuatahi o te ngohi

tauira mahi

  kia faanahohia = [1,2,3,4,5];

  arr.reduce(
  (accumulator, currentValue, currentIndex, ngohi) => {
    console.log(`accumulator ( I runga i te koru 1, Ko te uara tuatahi tenei, na te uara hoki o te koropiko o mua): ${accumulator}`);
    console.log(`currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[0]): ${currentValue}`);
    console.log(`currentIndex: ${currentIndex}`);
    console.log(`ngohi: ${ngohi}`);
    console.log('---');
    accumulator hoki + currentValue;
  }, 0
);

huaputa

accumulator ( I runga i te koru 1, Ko te uara tuatahi tenei, na te uara hoki o te koropiko o mua): 0
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[0]): 1
currentIndex: 0
ngohi: 1,2,3,4,5
---
accumulator ( I runga i te koru 1, Ko te uara tuatahi tenei, na te uara hoki o te koropiko o mua): 1
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[0]): 2
currentIndex: 1
ngohi: 1,2,3,4,5
---
accumulator ( I runga i te koru 1, Ko te uara tuatahi tenei, na te uara hoki o te koropiko o mua): 3
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[0]): 3
currentIndex: 2
ngohi: 1,2,3,4,5
---
accumulator ( I runga i te koru 1, Ko te uara tuatahi tenei, na te uara hoki o te koropiko o mua): 6
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[0]): 4
currentIndex: 3
ngohi: 1,2,3,4,5
---
accumulator ( I runga i te koru 1, Ko te uara tuatahi tenei, na te uara hoki o te koropiko o mua): 10
currentValue (Koropiko i roto i te ngohi, tīmata i faanahohia[0]): 5
currentIndex: 4
ngohi: 1,2,3,4,5
---