show only last 500 entries

websrc/components/RPlot.tsx

@@ -34,9 +34,16 @@ class RPlot extends Component<{}, PlotState> {
         })
 
         socket.on("new_tick", (data: NewTickData) => {
+            var new_x = [...this.state.x, data.tick]
+            var new_y = [...this.state.y, data.price]
+
+            // cutting to up to 500 entries (last 500)
+            var x = new_x.slice(Math.max(new_x.length - 500, 0))
+            var y = new_y.slice(Math.max(new_y.length - 500, 0))
+
             this.setState({
-                x: [...this.state.x, data.tick],
+                x: x,
-                y: [...this.state.y, data.price],
+                y: y,
             })
         })
     }