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Minor readme tweaks

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Sindre Sorhus 2020-01-30 00:51:52 +07:00
parent 863e26ad6a
commit f97029fd73
1 changed files with 15 additions and 15 deletions
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readme.md
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@ -509,29 +509,29 @@ Use generic type parameters with caution. They are only checked by the TypeScrip
import {assert} from '@sindresorhus/is';
async function badNumberAssumption(input: unknown) {
// Bad assumption about the generic type parameter fools the compile-time type system.
assert.promise<number>(input);
// `input` is a `Promise` but only assumed to be `Promise<number>`.
// Bad assumption about the generic type parameter fools the compile-time type system.
assert.promise<number>(input);
// `input` is a `Promise` but only assumed to be `Promise<number>`.
const resolved = await input;
// `resolved` is typed as `number` but was not actually checked at runtime.
const resolved = await input;
// `resolved` is typed as `number` but was not actually checked at runtime.
// Multiplication will return NaN if the input promise did not actually contain a number.
return 2 * resolved;
// Multiplication will return NaN if the input promise did not actually contain a number.
return 2 * resolved;
}
async function goodNumberAssertion(input: unknown) {
assert.promise(input);
// `input` is typed as `Promise<unknown>`
assert.promise(input);
// `input` is typed as `Promise<unknown>`
const resolved = await input;
// `resolved` is typed as `unknown`
const resolved = await input;
// `resolved` is typed as `unknown`
assert.number(resolved);
// `resolved` is typed as `number`
assert.number(resolved);
// `resolved` is typed as `number`
// Uses runtime checks so only numbers will reach the multiplication.
return 2 * resolved;
// Uses runtime checks so only numbers will reach the multiplication.
return 2 * resolved;
}
badNumberAssumption(Promise.resolve('An unexpected string'));