JavaScript: Elite JavaScript Coding From The Ground Up (DIY JavaScript Book 4) by Dvorjak Keith

Author:Dvorjak, Keith [Dvorjak, Keith]
Language: eng
Format: azw3
Published: 2018-05-28T16:00:00+00:00

Features of Closures

●The inner functions have access to outer function variables even after they have been executed, as we saw in our third example. We called the outer function before calling the inner function and even after returning the value, we could use the outer function parameters inside the inner function as it was preserved.

●Closures store references and not actual values to outer functions variables and can be edited, if needed (refer example 4).

●Closures provide a secure way of dealing with certain data, as we can save references to variables and prevent accidental changes.

//Example 4

//define a variable a = 5

var a = 5;

//define function add which adds 5 to a and returns value

var add = function(val){

a = a + val;//adding val to a

return a;//return a

}

a = 10; //update value of a

var result = add(5); //will make result equal to 15 and not 10 as //value of a is updated before the closure is called so saved //reference is updated with new reference

Closures are powerful but due care needs to be taken, as updated references can make your code full of bugs. Always make sure to use the capability carefully.

Note: Closures are functions or inner function which have preserved data referenced inside them from global or outer scopes.

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