import {Pipe, PipeTransform} from '@angular/core';
import {Product} from "./product";
@Pipe({
name: 'productFilter'
})
export class ProductFilterPipe implements PipeTransform {
transform(value: Product[], filterText?: string): Product[] {
filterText = filterText?filterText.toLocaleLowerCase(): null
return filterText ? value.filter((p: Product) => p.name
.toLocaleLowerCase().indexOf(filterText) !== -1) : value;
}
}
TS2322: Type 'string | null' is not assignable to type 'string | undefined'.
Type 'null' is not assignable to type 'string | undefined'.
and
TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
Type 'undefined' is not assignable to type 'string'.
Try with this
import {Pipe, PipeTransform} from '@angular/core';
import {Product} from "./product";
@Pipe({
name: 'productFilter'
})
export class ProductFilterPipe implements PipeTransform {
transform(value: Product[], filterText?: string): Product[] {
let pattern = filterText ? filterText.toLocaleLowerCase(): null;
return pattern ? value.filter((p: Product) => p.name.toLocaleLowerCase().indexOf(pattern) !== -1) : value;
}
}
If a filterText is not passed to the function then you got that error because you are trying to assign something to undefined.