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⚡️ TypeScript第3回講義 #4

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⚡️ TypeScript第3回講義 #4

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44 changes: 44 additions & 0 deletions pages/#3.tsx
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/*====================================================

【TypeScript入門 #3】型推論・型アノテーション・型アサーション、違い分かる？

====================================================*/

/*====================================================

型推論

====================================================*/

// let foo = 123;

// function double(x: number) {
// if (x > 0) {
// return;
// }
// return x * 2;
// }

/*====================================================

型アノテーション

====================================================*/

// function double(x: number): number | undefined {
// if (x > 0) {
// return;
// }
// return x * 2;
// }

/*====================================================

型アサーション

====================================================*/

// let foo = {} as { bar: number };
// let foo = <{ bar: number }>{};

// foo.bar = 1;