# Alert Expressions

Alert expressions modify widget graphical properties such as color, fill, and visibility based on series values and statistics.

# Example

• Change bar color to red if the threshold is exceeded.
• If the threshold is within the normal range, but is violated at least once during the last hour, change the bar color to yellow.
• Otherwise, apply green as the color.

[widget]
  type = bar
  color = yellowgreen

  alert-expression = max('1 hour') > 75 ? ((value > 75) ? 2 : 1) : false
  alert-style = (alert == 2) ? 'fill: red; stroke: red' : 'fill: yellow; stroke: yellow'

  [column]
    [series]
      entity = nurswgvml007  
  [column]
    [series]
      entity = nurswgvml006
  [column]
    [series]
      entity = nurswgvml010