使用array.push产生未定义

Question

I'm creating a polling app that should log the users ip, and which selection they voted for in addition to what the time was when they voted.

To do this I imagined creating an object for each 'vote' that included each of these as a property and then pushing that object into an array would suit my needs quite well.

Everything was running fine up until I tried to use push my object into my array. What I have currently says that that my array is undefined.

What exactly is happening? I tried using an index and setting votingArray[i] to the object, but that gave an undefined error as well.

Here is my code:

    //Vote for the pet passed into by user
function vote(pet, time){
    linkService.incrementCount(pet);
    trackVote(pet, time);

    res.render('vote', { 
    pet: pet
});
}

var votingArray = [];

function trackVote(pet, time) {

    var voteObject = {
        time: time,
        pet: pet,
        ip: req.ip
        };

console.log(voteObject);
    votingArray.push(voteObject);
    console.log(votingArray);

}

function showResults(){
res.render('results', { 
  votingArray: votingArray
    });
}

And here is the error in my console:

(Line 69 is 'votingArray.push(voteObject);')

Express started on http://localhost:8080; press Ctrl-C to terminate.
{ time: 1474584882143, pet: 'scout', ip: '::ffff:10.240.1.15' }
TypeError: Cannot read property 'push' of undefined
at trackVote (/home/ubuntu/workspace/Projects/projectTwo/app.js:69:14)
at vote (/home/ubuntu/workspace/Projects/projectTwo/app.js:51:6)
at /home/ubuntu/workspace/Projects/projectTwo/app.js:43:6
at Layer.handle [as handle_request] (/home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/layer.js:95:5)
at next (/home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/route.js:131:13)
at Route.dispatch (/home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/layer.js:95:5)
at /home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/index.js:277:22
at param (/home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/index.js:349:14)
at param (/home/ubuntu/workspace/Projects/projectTwo/node_modules/express/lib/router/index.js:365:14)

Edit:

Due to a lot of people suggesting that I've declared, but not instantiated the varriable 'votingArray' as an array, and that my snippets haven't included everything I've rewritten what I have to meet those comments and answers.

I'm still getting the same error about votingArray.push.

Here is my new code:

var votingArray = [];

//Vote for the pet passed into by user
function vote(pet, time){
    linkService.incrementCount(pet);

    var votingObject = 
    {
        ip: req.ip,
        pet: pet,
        timecode: time
    };

    votingArray.push(votingObject);

    res.render('vote', { 
    pet: pet
    });
}


function showResults(){
res.render('results', {
  votingArray: votingArray
    });
}

Answer 1

Your variable votingArray is not initialized. If you want it to be an array, you must replace the line

var votingArray;

with

var votingArray = []; // Empty array instance

Answer 2

initialize your array or pass it into the function instead of having a floating var in your file. We also can't see the usage of where trackVote is called in your question, but this would be my suggestion.

var votingArray = [];

function trackVote(pet, time) {

    var voteObject = {
        time: time,
        pet: pet,
        ip: req.ip
        };

    console.log(voteObject);
    votingArray.push(voteObject);
    console.log(votingArray);

}

to

function trackVote(pet, time) {
    var votingArray = [];
    var voteObject = {
        time: time,
        pet: pet,
        ip: req.ip
        };

    console.log(voteObject);
    votingArray.push(voteObject);
    console.log(votingArray);

}

or

function trackVote(pet, time, votingArray) {

    var voteObject = {
        time: time,
        pet: pet,
        ip: req.ip
        };

    console.log(voteObject);
    votingArray.push(voteObject);
    console.log(votingArray);

}