vue3-yuanma/test-dts/watch.test-d.ts

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import { ref, computed, watch } from './index'
import { expectType } from 'tsd'
const source = ref('foo')
const source2 = computed(() => source.value)
const source3 = () => 1
// eager watcher's oldValue will be undefined on first run.
watch(source, (value, oldValue) => {
expectType<string>(value)
expectType<string | undefined>(oldValue)
})
watch([source, source2, source3], (values, oldValues) => {
expectType<(string | number)[]>(values)
expectType<(string | number | undefined)[]>(oldValues)
})
// const array
watch([source, source2, source3] as const, (values, oldValues) => {
expectType<Readonly<[string, string, number]>>(values)
expectType<
Readonly<[string | undefined, string | undefined, number | undefined]>
>(oldValues)
})
// lazy watcher will have consistent types for oldValue.
watch(
source,
(value, oldValue) => {
expectType<string>(value)
expectType<string>(oldValue)
},
{ lazy: true }
)
watch(
[source, source2, source3],
(values, oldValues) => {
expectType<(string | number)[]>(values)
expectType<(string | number)[]>(oldValues)
},
{ lazy: true }
)
// const array
watch(
[source, source2, source3] as const,
(values, oldValues) => {
expectType<Readonly<[string, string, number]>>(values)
expectType<Readonly<[string, string, number]>>(oldValues)
},
{ lazy: true }
)