tslint / codelyzer / ng lint error: “for (… in …) statements must be filtered with an if statement”

Question

Lint error message:

src/app/detail/edit/edit.component.ts[111, 5]: for (... in ...) statements must be filtered with an if statement

Answer 1

If the behavior of for(... in ...) is acceptable/necessary for your purposes, you can tell tslint to allow it.

in tslint.json, add this to the "rules" section.

"forin": false

Otherwise, @Maxxx has the right idea with

for (const field of Object.keys(this.formErrors)) {