TSLint: Type number trivially inferred from a number literal, remove type annotation(no-inferrable-types)

This error means you are trying to set a variable like:

itemLength: number = 0;

The problem TypeScript has here, is that when you set this to 0, TypeScript already assumes this is a number. Therefore it is not needed.

Solution

No need to set the annotation, just remove it:

itemLength = 0;