How to remove whitespace from a string in typescript?

In my angular 5 project, with typescript I am using the .trim() function on a string like this, But it is not removing the whitespace and also not giving any error.

this.maintabinfo = this.inner_view_data.trim().toLowerCase();
// inner_view_data has this value = "Stone setting"

https://www.typescriptlang.org/docs/handbook/release-notes/typescript-1-4.html This docs clearly say that .trim() is part of the typescript.

What is best way to remove whitespace in from a string in typescript?