No TypeScript error in Angular app when assigning a string to a number data type

Today, I encountered some confusion when my app started acting strangely. It turns out that I mistakenly assigned a string to a number without receiving any error alerts. Any thoughts on why this happened?

id:number;

Later on:

this.id = ActiveRoute.params.id; //(which was actually a string)
//perform some iteration (n=this.id) times

I noticed that my iteration only executed once, even though I would have expected to be notified of the mismatch in data types when assigning to id.

(edited attribute originally based from memory^)

angulartypescript

Answer №1

It seems like ActiveRoute is presumed to be of the type ActivatedRouteSnapshot. In this case, the property type params is expected to be of type Params, which adheres to the interface defined as { [key: string]: any }

The crucial part here is the usage of any. TypeScript lacks knowledge about the types of properties in the Params object, hence it relies on your assurance when assigning it to a property with type number. Using any means that TypeScript permits assignment to any type, so you must ensure accurate assignments.

For more information, refer to the documentation: https://angular.io/api/router/ActivatedRouteSnapshot#params

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