Why is my javascript not running in order?

Question

In code1, it outputs undefined as expected. However code2 outputs the array already with the "hello" pushed inside. I don't understand why it didn't run the code in order.

function drawChart(chart) {
        console.log(chartData) //code1
        var chartData = [];
        console.log(chartData) //code2

       chartData.push("hello")
}