highcharts - Changing the scale of yAxis on Highstock to draw plot line -

i have data, 200, should plotted yaxis line. default min , max value set 300 , 500 respectively. how can draw yaxis plotline dynamically , how change scale of yaxis dynamically?

thanks in advance.

1) add plotline use chart.yaxis[0].addplotline(object). see docs

2) change extremes use chart.yaxis[0].setextremes(min, max). see docs