27 lines
852 B
TypeScript
27 lines
852 B
TypeScript
// @lib: es6
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// @keyofStringsOnly: true
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const sym = Symbol();
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const num = 0;
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const obj = { num: 0, str: 's', [num]: num as 0, [sym]: sym };
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function set <T extends object, K extends keyof T> (obj: T, key: K, value: T[K]): T[K] {
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return obj[key] = value;
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}
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const val = set(obj, 'str', '');
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// string
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const valB = set(obj, 'num', '');
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// Expect type error
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// Argument of type '""' is not assignable to parameter of type 'number'.
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const valC = set(obj, sym, sym);
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// Expect type error
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// Argument of type 'unique symbol' is not assignable to parameter of type "str" | "num"
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const valD = set(obj, num, num);
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// Expect type error
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// Argument of type '0' is not assignable to parameter of type "str" | "num"
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type KeyofObj = keyof typeof obj;
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// "str" | "num"
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type Values<T> = T[keyof T];
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type ValuesOfObj = Values<typeof obj>; |