I am making a web page that allows the user to view charts. It is important for the user to know how recent the charts were updated to the site. Next to the charts, I want a label that states the date the chart was updated on the site. The issue is I am only able to get lastModified for the document. This code gives an undefined error.

Thank you!

    var file = 'chart.png'
    document.write(file.lastModified)
/*     document.getElementById("date").innerHTML = document.lastModified; */
</script>