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JS配列にあれば削除なければ追加

JavaScript
TypeScript

Last updated at 2022-08-23Posted at 2022-08-03

コード

const arr = [1,2,3,4]
const x = 5

// indexOf()による判断
const index = arr.indexOf(x);
// index < 0: なければ，追加
// index >= 0: ある，削除
index < 0 ? arr.push(x) : arr.splice(index, 1)

console.log(arr)
// [1,2,3,4,5]

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