无法获取javascript增量，最新变量值进入隐藏输入字段

so I'm trying to get javascript variable value into hidden input field and it sort of work, but I get default variable value from html5games.pingpong.js. If I set variable myVar = 0; I get 0 in an input field, but it's a game and I can't get the value of bestScore to increment.

html5games.pingpong.js

var pingpong = {
scoreA : 0, // score for player A
scoreB : 0, // score for player B
bestScore : 0 
};

function movePaddles() {
pingpong.bestScore += 5;
}

PHP: test.php

<input id="score" type="hidden" name="bestScore">

<script>
document.getElementById('score').value = pingpong.bestScore; 
</script>

Here is an example using jQuery (you can try it at https://jsfiddle.net/07tb4bp9/):

var pingpong = {
    scoreA : 0, // score for player A
    scoreB : 0, // score for player B
    bestScore : 0 
};

function movePaddles() {
    pingpong.bestScore += 5;
    $('#score').val(pingpong.bestScore);
    // Without jquery : document.getElementById('score').value= pingpong.bestScore; 
}

movePaddles();

You need to update the value when it changes.

function movePaddles() {
pingpong.bestScore += 5;
document.getElementById('score').value = pingpong.bestScore; 
}