从回调函数内部获取变量值

Question

I am trying to pull a variable's value from a callback function. What am I doing wrong here?

var storyList = [];
var storyTemp ={};

// get list of all stories
db.getAllStoriesSet(function(err, reply) {
    if (err) throw err;
    else {
        storyList = reply;
        console.log("storylist inner: " + storyList);
    };
});
console.log("storylist outer: " + storyList);

in the above code, I am expecting the inner and outer storylist values to be same. however the outer storyList value still comes as a null list.

EDIT: to add to the question. I have initialized a variable storyList outside the async function. i am then taking the reply from the async function and putting it in the variable storyList. I was hoping to cheat my way out of the async pit of slow and brutal death that I have apparently dug for myself. shouldnt it have worked?

Answer 1

If getAllStoriesSet is asynchronous, then the line following its call is called before the callback is executed. So storyList is just like it was before the call.

That's the reason why you provide a callback : you must put inside the callback the code which needs the value of reply .