Optional Properties Not all properties of an interface may be required. Some exist under certain conditions or may not be there at all. These

Sections The guide is broken down into the following sections.

Using npm npm install -g typescript@next

typeof type guards Let’s go back and write the code for the version of padLeft that uses union types. We could write

Decorator Composition Multiple decorators can be applied to a declaration, as in the following examples:

Duo

Namespacing As we add more validators, we’re going to want to have some kind of organization scheme so that we can keep track of our types and

compileOnSave Setting a top-level property compileOnSave signals to the IDE to generate all files for a given tsconfig

Using with export = or import An important rule is that export and import declarations

Function Parameter Bivariance When comparing the types of function parameters, assignment succeeds if either the source parameter is assignable