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JLarky opened this issue Dec 23, 2017 · 6 comments · Fixed by #1842
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Wrong typescript declarations for update method #1466

JLarky opened this issue Dec 23, 2017 · 6 comments · Fixed by #1842
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@JLarky
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JLarky commented Dec 23, 2017 •
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What happened

update(key: K, updater: (value: V) => V): this;

here updater has wrong type, should be updater: (value?: V) => V) if key doesn't exist

How to reproduce

const good = I.Map<string, I.List<string>>().update("noKey", I.List(), a => a.map(x => x));
const bad = I.Map<string, I.List<string>>().update("noKey", a => a.map(x => x));
const fixed = I.Map<string, I.List<string>>().update("noKey", undefined as any, (a: undefined | I.List<string>) => a.map(x => x));

image

Here good works as expected, fixed shows error message that I would expect to see in this case Object is possibly 'undefined', but bad doesn't show any errors while crashing at run time with Uncaught TypeError: Cannot read property 'map' of undefined

Maybe there need to be a function that is updateIfKeyExist that would have (value: V) => V type, but right now type is misleading and causes run time issues.
@JLarky
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JLarky commented Dec 23, 2017

I also noticed that you can return undefined from updater and it will delete the key from map, so I guess it's a updater: (value: V | undefined) => V | undefined)

@remi-blaise
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@JLarky In Typescript undefined extends any type, so the updater type is updater: (value?: V) => V) which is fine.

@JLarky
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JLarky commented Dec 31, 2017 via email

@remi-blaise
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Does Immutable support --strict flag ?

@JLarky
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JLarky commented Jan 2, 2018 via email

@JLarky
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JLarky commented Feb 15, 2018

Noticed similar issue with mapEntries method. It allows you to return undefined instead of tuple to remove entry from collection so

   mapEntries<KM, VM>(
      mapper: (entry: [K, V], index: number, iter: this) => [KM, VM],
      context?: any
    ): Map<KM, VM>;

should be

   mapEntries<KM, VM>(
      mapper: (entry: [K, V], index: number, iter: this) => [KM, VM] | undefined,
      context?: any
    ): Map<KM, VM>;

@ghost ghost mentioned this issue Jun 17, 2020
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@Methuselah96 Methuselah96 mentioned this issue Oct 17, 2020
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@jdeniau jdeniau mentioned this issue Jul 6, 2021
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@cypherfunc cypherfunc mentioned this issue Feb 6, 2023
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Fix type signature of update and mapEntries immutable-js/immutable-js
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@JLarky @Methuselah96 @remi-blaise