ROC (Rate of Change)

ROC measures the percentage change between the current price and the price N periods ago. It oscillates around zero, with positive values indicating upward momentum.

Declaration

function init(ctx) {
  ctx.indicator('roc', 'ROC', { period: 12, source: 'close' });
}

Options

Option	Type	Default	Description
`period`	`number`	12	Lookback period
`source`	`string`	`'close'`	Price source

Output

Returns a single number[] series (percentage values).

Accessing Values

function onBar(ctx, i) {
  const roc = ctx.ind.roc[i]; // e.g., 2.5 = 2.5% gain over period
}

Use Cases

Momentum Filter

function onBar(ctx, i) {
  const roc = ctx.ind.roc[i];
  
  // Only take trades when momentum is positive
  if (roc > 0 && q.crossOver(ctx.ind.fast, ctx.ind.slow, i)) {
    ctx.order.market('ASSET', 1, { signal: 'buy', reason: 'positive_momentum' });
  }
}

Zero-Line Cross

function onBar(ctx, i) {
  const roc = ctx.ind.roc[i];
  const prevRoc = ctx.ind.roc[i - 1];
  
  if (prevRoc <= 0 && roc > 0) {
    ctx.order.market('ASSET', 1, { signal: 'buy', reason: 'roc_positive' });
  }
}

Calculation

$$ROC = \frac{Price_t - Price_{t-N}}{Price_{t-N}} \times 100$$

TRIX - Smoothed rate of change
MACD - Momentum via EMA difference
RSI - Bounded momentum oscillator