RSI (Relative Strength Index)

The RSI measures the speed and magnitude of recent price changes on a 0-100 scale. It identifies overbought (>70) and oversold (<30) conditions.

Declaration

function init(ctx) {
  ctx.indicator('rsi', 'RSI', { period: 14, source: 'close' });
}

Options

Output

Returns a single number[] series with values between 0 and 100.

Accessing Values

function onBar(ctx, i) {
  const rsiValue = ctx.ind.rsi[i];
}

Use Cases

Overbought / Oversold

function onBar(ctx, i) {
  const rsi = ctx.ind.rsi[i];
  
  if (rsi < 30) {
    ctx.order.market('ASSET', 1, { signal: 'buy', reason: 'oversold' });
  }
  if (rsi > 70) {
    ctx.order.close('ASSET', { signal: 'sell', reason: 'overbought' });
  }
}

RSI Divergence

function onBar(ctx, i) {
  const rsi = ctx.ind.rsi[i];
  const close = ctx.series.close[i];
  const prevRsi = ctx.ind.rsi[i - 5];
  const prevClose = ctx.series.close[i - 5];
  
  // Bullish divergence: price makes lower low, RSI makes higher low
  if (close < prevClose && rsi > prevRsi && rsi < 40) {
    ctx.order.market('ASSET', 1, { signal: 'buy', reason: 'bullish_divergence' });
  }
}

Value Ranges

Calculation

$$RSI = 100 - \frac{100}{1 + RS}$$

Where $RS = \frac{\text{Average Gain}}{\text{Average Loss}}$

Related

• Stochastic RSI - RSI fed into stochastic formula
• CCI - Another mean-reversion oscillator
• Williams %R - Similar overbought/oversold indicator