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Know the limits a script runs within. They are the same on every device and every plan. Past the step budget a script stops with OX2200, naming the line of the loop or call, and keeps what it had drawn. Counting steps rather than time makes the limit behave the same on a phone and a desktop. A run that takes more than 5 seconds is stopped, and the same script with the same settings is not loaded again on the page until you change it.

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Keeping a script fast

  • Work per bar, not per bar times history: keep running totals in state rather than looping back over old bars.
  • Draw only on the newest bar (chart.isLast) when only the newest bar’s drawing matters.
  • Sum events into tallies in their handlers; do the per-bar work once in onBar or onClose.

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The same result everywhere

A script gives the same output for the same data in every browser:
  • no clock, timers or Math.random: random(seed) gives the same numbers for the same seed;
  • Math is the engine’s own, a port of fdlibm, so exp, log, pow and the trigonometric functions give the same bits in Chrome, Safari and Firefox;
  • ta.* follow TradingView’s formulas, seeds and running sums.
Scripts run in a worker of their own, served with a policy that allows no network access, and output is checked against the script’s declaration before it is drawn.

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Next step

Check scripts outside the terminal, or have an AI write them, with tools for agents.
Last modified on October 16, 2026