Question

<script type="text/javascript">
        function vote(element, val){
            prev_vote=0;
            vote = 100
            can_vote = element.find('.vote-permission').attr('value')
            alert(can_vote);
            if (can_vote=='yes'){
                if (prev_vote==0){ 
                    alert("previous vote is 0");
                    // user has not cast vote for image before
                    vote_score = vote + val;
                    element.find('.vote-count-post').text(vote_score);
                }
                else if (prev_vote != 0){
                    // user has cast a vote before
                    if (prev_vote == 1 && val == -1){
                        vote_score = vote - 2;
                        element.find('.vote-count-post').text(vote_score);
                    }
                    else if (prev_vote == -1 && val == 1){
                        vote_score = vote + 2;
                        element.find('.vote-count-post').text(vote_score);
                    }
                }
            }
        };

        $(document).on('click', '.votedown', function(e){
            alert($(e.target).prev().text());
            vote($(e.target).parent(), -1);
            alert('vote down is done');
            });

        $(document).on('click', '.voteup', function(e){
            $(e.target).css('background-position', '0 -222px');
            vote($(e.target).parent(), 1);
            alert('vote up is done');
            });
    </script>

The above javascript functions are scaffold for an up and down voting system I am implementing. When a click is made to the upvote or downvote button for the first time the functions execute as expected with vote() called but on a second click the vote() function is said to be not defined. Any ideas why?

Answer 1

The function is deleting itself with

vote = 100

It replaces the value of the vote variable in the outside scope (was the function, is now a number).

You could prevent it with a var keyword but you should not use twice the same name as it breaks readability.