> ## Documentation Index
> Fetch the complete documentation index at: https://docs.0xarchive.io/llms.txt
> Use this file to discover all available pages before exploring further.
# 4h EMA
> An EMA of 4-hour bars on any chart, with no lookahead.
Load it on BTC 15m in the terminal, then change its settings or open it in the script editor.
A 20-period EMA of the 4-hour closes, drawn on a 15-minute chart. It steps when each 4-hour bar closes.
## How it works
`bars({ interval: '4h' })` is a second stream with its own handler, which updates the EMA. The chart's handler reads `ema.confirmed`: the value as of the last closed 4-hour bar. That is the [no-lookahead rule](/terminal/guides/data#as-of-no-lookahead): history only ever sees what was known at the time, so the line is drawn where it would have been live.
## The script
```ts higher-timeframe.ts theme={"theme":"github-dark"}
// A 4h EMA on any chart. Reading another stream gives its last closed value: no lookahead.
indicator('4h EMA', { overlay: true });
const length = input.int('Length', 20, { min: 1 });
const chart = bars();
const h4 = bars({ interval: '4h' });
const ema = ta.ema(length);
const line = plot.line('4h EMA', { width: 2 });
h4.onBar(() => {
ema.update(h4.close);
});
chart.onBar(() => {
line.set(ema.confirmed);
});
```
## Next step
See the next example, [Anchored VWAP bands](/terminal/examples/anchored-vwap).
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