flat()
const twoDimensionsArray = [[1a, 1b, 1c], [2a, 2b, 2c], [3a, 3b, 3c]] twoDimensionsArray.flat() => ['1a', '1b', '1c', '2a', '2b', '2c', '3a', '3b', '3c']
flatMap()
flatMap()を使うと、
オブジェクトの配列内にある配列の平坦な連想配列を作れる
const twoDimensionsObjArray = [ { key: 1, value: 'aaa', array: [ { aryKey: 10, aryVal: 'a' }, { aryKey: 20, aryVal: 'b' } ] }, { key: 2, value: 'bbb', array: [ { aryKey: 30, aryVal: 'c' }, { aryKey: 40, aryVal: 'd' } ] } ] twoDimensionsObjArray.flatMap((obj)=>obj.array) => [ { aryKey: 10, aryVal: 'a' }, { aryKey: 20, aryVal: 'b' }, { aryKey: 30, aryVal: 'c' }, { aryKey: 40, aryVal: 'd' } ]
map()とflat()をそれぞれ実行しても同じ
const twoDimensionsObjArray = [ { key: 1, value: 'aaa', array: [ { aryKey: 10, aryVal: 'a' }, { aryKey: 20, aryVal: 'b' } ] }, { key: 2, value: 'bbb', array: [ { aryKey: 30, aryVal: 'c' }, { aryKey: 40, aryVal: 'd' } ] } ] const mappedArray = twoDimensionsObjArray.map((obj)=>obj.array) => [ [ { aryKey: 10, aryVal: 'a' }, { aryKey: 20, aryVal: 'b' } ], [ { aryKey: 30, aryVal: 'c' }, { aryKey: 40, aryVal: 'd' } ] ] mappedArray.flat() => [ { aryKey: 10, aryVal: 'a' }, { aryKey: 20, aryVal: 'b' }, { aryKey: 30, aryVal: 'c' }, { aryKey: 40, aryVal: 'd' } ]