What are JavaScript closures and how do JavaScript closures work?
What are JavaScript closures and how do JavaScript closures work?
10307-Jul-2023
Updated on 10-Jul-2023
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What are JavaScript closures and how do JavaScript closures work?
Aryan Kumar
10-Jul-2023In JavaScript, a closure is a function that has access to the variables of its enclosing function, even after the enclosing function has finished executing. This is because a closure is a combination of a function and the lexical environment within which that function was declared. This environment consists of any local variables that were in-scope at the time the closure was created.
Here is an example of how a closure works:
Code snippet
In this example, the
innerFunc()
function has access to thename
variable, even though theouterFunc()
function has finished executing. This is because theinnerFunc()
function is a closure, and it has access to the lexical environment of theouterFunc()
function.Closures are often used to create reusable functions that can access shared data. For example, you could use a closure to create a function that can format a date, regardless of the current date. The closure would have access to the current date, even though the function was defined before the date was known.
Closures can also be used to create private variables. A private variable is a variable that can only be accessed by the function that created it. You can create a private variable by declaring it inside a closure. For example, the following code creates a private variable called
count
:Code snippet
In this example, the
count
variable is only accessible from within theinnerFunc()
function. This is because thecount
variable is declared inside the closure.Closures are a powerful tool that can be used to create reusable and efficient JavaScript code. If you are not familiar with closures, I recommend taking some time to learn more about them. They can be a valuable asset in your JavaScript toolbox.