Adding the JavaScript

Now that we have discussed a little of the trigonometry necessary to draw our SVG chart, let me step through the JavaScript we need to add to make our code work:

<script>
    document.getElementById("min_angle").onchange = function() {
        var min_angle = Number(this.value);
        var max_angle = Number(document.getElementById         
                        ("max_angle").value);
 
        if( min_angle >= max_angle ) {
            max_angle = min_angle + 1;
            document.getElementById("max_angle").value = max_angle;
        }
 
        if( min_angle < this.min ) {
            min_angle = this.min;
            this.value = min_angle;
        }
        SetPie( min_angle / 180 * Math.PI, max_angle / 180 * Math.PI );
    }
 
    document.getElementById("max_angle").onchange = function() {
        var min_angle...