Stochastic Oscillator on TradingView — Pine Script v5 Source

Pine Script has ta.stoch for the raw %K, and building the slow stochastic on top of it is two ta.sma calls. Here’s the version from the explainer, zones and all.

What you’ll need

• A TradingView account (free tier is fine)
• The Pine Editor

The source

//@version=5
indicator("AlgoGen Stochastic", shorttitle="AG Stoch", overlay=false)

kLen   = input.int(14, "%K length")
smooth = input.int(3,  "%K smoothing")
dLen   = input.int(3,  "%D length")

rawK = ta.stoch(close, high, low, kLen)   // 100 * (close - LL) / (HH - LL)
k    = ta.sma(rawK, smooth)               // slow %K
d    = ta.sma(k, dLen)                     // %D

plot(k, "%K", color=#2a78d6, linewidth=2)
plot(d, "%D", color=#eb6834, linewidth=2)

h80 = hline(80, "Overbought", color=color.gray)
h20 = hline(20, "Oversold",   color=color.gray)
fill(h80, hline(100), color=color.new(#e34948, 90))
fill(hline(0), h20,   color=color.new(#1baf7a, 90))

ta.stoch(close, high, low, kLen) gives raw %K directly — note the argument order (source, high, low). Smoothing it once yields the slow %K, and averaging that gives %D. The fill calls shade the overbought/oversold zones like the output chart.

Cross alerts

alertcondition(ta.crossover(k, d)  and k < 20, "Stoch bull", "%K crossed up in oversold")
alertcondition(ta.crossunder(k, d) and k > 80, "Stoch bear", "%K crossed down in overbought")

Colouring the momentum zones

A nice touch is tinting the %K line itself when it’s in an extreme, so the state reads at a glance without hunting for the level lines:

kColor = k > 80 ? #e34948 : k < 20 ? #1baf7a : #2a78d6
plot(k, "%K", color=kColor, linewidth=2)

Blue in the neutral zone, red when overbought, green when oversold — the colour is redundant with position (never the only signal), which keeps it readable for colour-blind viewers too.

Adding it

1. Paste and Add to chart — it opens in its own pane.
2. For the raw fast stochastic, plot rawK and ta.sma(rawK, dLen) instead.
3. Right-click → Add alert to wire up the cross conditions above.

Gotchas

• Argument order. ta.stoch takes (source, high, low, length). Swapping high and low silently gives nonsense.
• Slow vs fast. The extra ta.sma(rawK, smooth) is the only difference. “14, 3, 3” is the slow version.
• Divide-by-zero. ta.stoch handles a flat range internally, so you won’t get inf — but be aware the value can flatline in a dead range.

Same indicator elsewhere: Python, MQL5, EasyLanguage, NinjaScript. Then test a stochastic rule in AlgoGen.

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This post is educational, not financial advice. Indicators describe the past; they don’t predict the future. Backtest anything before you risk real money on it.