In TypeScript, closures can be implemented using nested functions. A closure is a function that has access to variables in its parent function, even after the parent function has returned.
Here is an example of a closure in TypeScript:
index.ts226 chars13 lines
In this example, outerFunction
returns innerFunction
. innerFunction
has access to the outerVariable
in outerFunction
, even though outerVariable
is not defined in innerFunction
. This is because innerFunction
is a closure that "closes over" the variables in its parent function.
When outerFunction
is called and closure
is assigned the result, outerVariable
is defined and initialized to 'I am outside!'
. When closure
is called later with closure()
, console.log(outerVariable)
logs 'I am outside!'
.
As a result, closures are a powerful feature of JavaScript and TypeScript that can be used to create functions with persistent state across multiple invocations.
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