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feat(compiler): Support "in" operator in Angular templates #38560
Description
🚀 feature request
Description
I'd like to have your opinions about supporting "in" operator in html templates. Let's say I have an object of a union type A | B. I'd like to use the 'in' operator to differentiate type.
Something like:
export interface A {
a: number
}
export interface B {
b: string
}
export type MyUnionType = A | B;
item: MyUnionType = {
a: 1
}
<div *ngIf="'a' in item">
I'm expecting item is no longer of type A | B, but only A
{{item.a}}
</div>
Here is a stackblitz
Reacted by Aleksei Lebedev, Dexter Tad-y, Samuel Fernández, Rafael Mestre, Ertunga Bezirgan, Indraraj, Sheik Althaf, Vsevolod Vinogradov, Aleksey Zheleznyakov, Denis Bendrikov and 4 more
Activity
[-]Support "in" operator in Angular teplate[/-][+]Support "in" operator in Angular templates[/+]angular-robot commentedon Jun 4, 2021
Just a heads up that we kicked off a community voting process for your feature request. There are 20 days until the voting process ends.
Find more details about Angular's feature request process in our documentation.
angular-robot commentedon Jun 24, 2021
Thank you for submitting your feature request! Looks like during the polling process it didn't collect a sufficient number of votes to move to the next stage.
We want to keep Angular rich and ergonomic and at the same time be mindful about its scope and learning journey. If you think your request could live outside Angular's scope, we'd encourage you to collaborate with the community on publishing it as an open source package.
You can find more details about the feature request process in our documentation.
alxhub commentedon Jul 8, 2021
In this spirit of aligning Angular expression syntax with JS expression syntax, I'm moving this into our triage process for further discussion.
[-]Support "in" operator in Angular templates[/-][+]feat(compikler): Support "in" operator in Angular templates[/+][-]feat(compikler): Support "in" operator in Angular templates[/-][+]feat(compiler): Support "in" operator in Angular templates[/+]petebacondarwin commentedon Oct 15, 2021
This is being tracked in the aggregate issue of #43485 for which we need to create a project proposal.
alxhub commentedon Feb 1, 2022
^ closing as we're discussing these improvements to template expression syntax holistically, along the theme of unifying Angular syntax with JS.
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