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Documentation Index

Fetch the complete documentation index at: https://docs.darvas.app/llms.txt

Use this file to discover all available pages before exploring further.

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Overview

ctx is a global object available everywhere in your script. Inside onBar it reflects the current bar being processed. All OHLCV accessors are functions that accept an optional offset argument - the number of bars to look back from the current bar. 
onBar(() => {
  const close  = ctx.close();    // current bar close
  const prev   = ctx.close(1);   // previous bar close
  const change = close - prev;
});

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Bar metadata

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ctx.length
number
Total number of bars in the current window.
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ctx.bar
string
Current timeframe string, e.g. "1H", "4H", "1D".
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ctx.instId
string
Current instrument, e.g. "BTC-USDT-SWAP".
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ctx.i()
number
Current bar index. 0 = oldest bar in window, ctx.length - 1 = newest.
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ctx.barIndex()
number
Alias for ctx.i().
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ctx.isLast()
boolean
true when processing the most recent (realtime) bar.

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OHLCV accessors

All accessors accept an optional offset - bars back from the current bar. offset = 0 (default) is the current bar; offset = 1 is the previous bar.
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ctx.open(offset?)
number | null
Open price.
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ctx.high(offset?)
number | null
High price.
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ctx.low(offset?)
number | null
Low price.
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ctx.close(offset?)
number | null
Close price.
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ctx.volume(offset?)
number | null
Volume.
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ctx.time(offset?)
number | null
Bar open time as unix seconds (UTC).

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Composite price accessors

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ctx.hl2(offset?)
number | null
(high + low) / 2
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ctx.hlc3(offset?)
number | null
(high + low + close) / 3 - typical price, commonly used with ta.cci.
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ctx.ohlc4(offset?)
number | null
(open + high + low + close) / 4

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Passing accessors as sources

The OHLCV accessors are function references - they match the (offset?) => number | null signature that ta.* functions expect as their source argument: 
// Correct: pass ctx.close as a function reference
const rsi = ta.rsi(ctx.close, 14);

// Correct: input.source returns the same shape
const src = input.source("Source", "close");
const rsi2 = ta.rsi(src, 14);

// Wrong: calling ctx.close() gives you a scalar, not a source
// const rsi3 = ta.rsi(ctx.close(), 14); // TypeError

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Example: multi-bar lookback

onBar(() => {
  const c0 = ctx.close();   // current close
  const c3 = ctx.close(3);  // close 3 bars ago

  // Detect 3-bar momentum
  const momentum = c0 - c3;
  plot("3-bar Momentum", momentum);

  // Log bar info on last bar
  if (ctx.isLast()) {
    console.log(ctx.instId, ctx.bar, "index:", ctx.i());
  }
});

Inputs

input.source returns the same function shape.

Moving averages

ta.* functions that accept a source parameter.

NaN handling

What to do when ctx.close returns null.