Based off of MasaNakamura's implementation, modified to show high & super-high momentum thresholds. In addition, coloring the trend line by the prevailing trend direction from the DI (Red if down, Green if up) allows you to remove the DI if you want to reduce chart clutter!
"The Average Directional Index (ADX), Minus Directional Indicator (-DI) and Plus Directional Indicator (+DI) represent a group of directional movement indicators that form a trading system developed by Welles Wilder.... The Plus Directional Indicator (+DI) and Minus Directional Indicator (-DI) are derived from smoothed averages of these differences, and measure trend direction over time. These two indicators are often referred to collectively as the Directional Movement Indicator (DMI).
The Average Directional Index (ADX) is in turn derived from the smoothed averages of the difference between +DI and -DI, and measures the strength of the trend (regardless of direction) over time.
Using these three indicators together, chartists can determine both the direction and strength of the trend....
At its most basic, the Average Directional Index (ADX) can be used to determine if a security is trending or not. This determination helps traders choose between a trend-following system or a non-trend-following system. Wilder suggests that a strong trend is present when ADX is above 20..."