Function calling in Javascript with double brackets

Question

When I call function hi()() with double brackets the function displays hi output and it will also give error saying, that hi is not functi

Answer 1

()() means calling a function and if returns another function second parenthesis will call it.Please find below example :

function add(x){
    return function(y){
        return x+y;
    }
}

add(3)(4)

output: 7

in above case add(4) will be called for add function and add(3) will be called for returned function. here value of parameter x is 3 and parameter y is 4.

Please note : we use parenthesis for function call.