I want the objects I use in my TypeScript code to let me set multiple properties on them in one go. My objects must have a method setProps such that when given a properly typed map of properties, the method sets the corresponding properties on the objects.
I want the objects I use in my TypeScript code to let me set multiple properties on them in one go. My objects must have a method
setPropssuch that when given a properly typed map of properties, the method sets the corresponding properties on the objects.
I have a base class, say
BaseObject, that has the public
setProps must take parameters that are compatible with the instance of a class derived from BaseClass. This is achieved with generics. The method will look like the following piece of code:
I constrain the type parameter
T to represent a type that inherits from
BaseObject by using the syntax
<T extends BaseObject>.
Now, I want to assign the properties of the passed parameter to the object on which
setProps was called. To achieve this, I proceed as shown in the following excerpt:
for in loop gets all the keys in
values and for each such property, if its value is not null, assigns it to the same property on the calling object.
In TypeScript, Generic Types enable us to define a placeholder type for a variable we do not know enough yet to precise its type. Consider the following snippet:
Type systems are typically categorized as either structural or nominal. Languages like Java and Scala have primarily nominal type systems, whereas a language like Typescript has a structural type system. Let’s take a brief look at both systems.
A type system is a set of rules for performing various consistency and correctness checks in a program. There are various definitions and classifications for type systems
Type inference is the automatic detection of the data type of an expression in a programming language. This feature is present in some strongly statically typed languages, including TypeScript.
In the above case the input and output are specified as type any which defeats the whole purpose of TypeScript as it will never find a type error if anything is allowed. Instead we could use generic syntax as denoted by <> to pass in a generic type when the function is called.