Highcharts test tool

HTML

<div id="container1" style="height: 50px"></div>
<div id="container2" style="height: 50px"></div>

JavaScript

var withNulls = [null, 12, 23, 45, 3.44, null, 0];
$('#container1').html('[' + withNulls.join(', ') + ']');

var noNulls = withNulls.map(function (item) {
    return (item === null) ? 0 : item;
});

$('#container2').html('[' + noNulls.join(', ') + ']');