JavaScript Function within a function undefined [duplicate]

Question

Can someone explain to me why the second function within the first function is undefined?

var a = 1

function abc () { 
    alert(a); 
        function xyz () { 
            alert(a); 
        } 
}

https://jsfiddle.net/kp950/yLs73cth/

You should include your HTML in your question here for it to make sense. — James Thorpe
– James Thorpe, Commented Mar 14, 2016 at 12:31
It's not undefined inside abc. It's however not in the global scope, somewhat obviously. — deceze
– deceze ♦, Commented Mar 14, 2016 at 12:31
Regarding the dupe - inline event handlers in things like onclick attributes usually require their targets to be available within the global scope. It's also quite a dated technique - you should look into using event listeners, which allow you to arbitrarily nest functions and still have them respond to things like button clicks. — James Thorpe
– James Thorpe, Commented Mar 14, 2016 at 12:33
@ozil "Uncaught TypeError: abc(...).xyz is not a function" - the alert you're seeing is the one from the outer function. You want onclick="abc()();" to get it to run the returned function. You get two alerts though, so I'm not sure what this solves. — James Thorpe
– James Thorpe, Commented Mar 14, 2016 at 12:36

brk · Accepted Answer · 2016-03-14 12:31:51Z

1

xyz is an inner function which is private to abc function. You cannot call xyz unless you make it public

answered Mar 14, 2016 at 12:31

brk

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2 Comments

spex5 Over a year ago

It seems like you can though by calling abc().xyz() jsfiddle.net/yLs73cth/4

James Thorpe Over a year ago

@spex5 See my comments under the question related to that - xyz isn't actually running there, it's throwing an error. And @user2181397 said "unless you make it public". Returning the inner function from the outer one is making it public.

bwegs · Accepted Answer · 2016-03-14 12:32:18Z

1

This is due to the scope at which you are trying to execute xyz() (globally). xyz() can only be run inside of abc() - where it is defined in the local scope.

answered Mar 14, 2016 at 12:32

bwegs

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