In JavaScript to understand a pure function is so important to know when you are very dependable in functional programming. Every pure function is a “Function” but every function is not a “Pure Function”. To be a pure function there should have some characteristics.
- Always depends on own arguments. Like same input, same output.
- No Side effects & it will not change the variable value outside of own scope.
let val1 = 1
let val2 = 2
function pureFunction() {
return val1 * val2
}
pureFunction()
The above example is animpurefunction & cause this function using outside scope variable. if the val1 or val2 will change the function will give different output. so its not the charateristic of pure function.
function pureFuncion() {
let val1 = 6
let val2 = 4
return val1 * val2
}
pureFuncion()
The above example is pure function, cause there is nothing going to change outside of its own scope. It always depends on his own scope.
I just tried to give you the very basic concept what is pure and impure function. To know more, you can search on google for deep-inside.
