Why in components or directives do the metadata or decorators have the
@ symbol (e.g.
What is the purpose of it, and when should I use it?
It stands for decorators. It is not TypeScript specific.
For up to date information about their standard implementation and when it will finally be released (future ECMAScript versions), see this page:
And as @hardikModha mentioned, you can also look up the TypeScript handbook:
Answered By – unional