feat(opreator): Logical assignment operatorsの追加 #1334
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azu
commented
Jun 27, 2021
| <!-- doctest:meta:{ "ECMAScript": 2021 } --> | ||
| ```js | ||
| // `a`がtrueのときに、`a`へ`b`を代入する | ||
| a &&= b; |
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これぐらい的な例を増やすの微妙な感じがするので、やっぱり対応しないほうが良さそうな気がする。
a &&= b;は
a && (a = b);という意味となる。a がtruthの場合のみassignが発生するという形になる。
つまり実際には次のようなイメージのコード。
if( a ) {
a = b;
}a ??= b に対応するifの書き方がない。
if( a == null ) {
a = b
}ではあるけど ?? がなくなっている。
a ?? (a = b);
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入れるならチートシートにも入れるべき。 本書の目的ではないことを考えると、現時点では含める必要がないと判断したので閉じる |
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&&=、||=、??=を追加他の
+=みたいなものとはメンタルモデルが異なるので、あんまり扱わないほうが良さそうな感じがする。参考: