How Common Technical Indicators Are Computed from Price Data

Summary

This document presents a hand-built technical analysis library in JavaScript, with partial versions in other languages. It explains the calculations behind common indicators, including moving averages, MACD, Bollinger Bands, KDJ, RSI, OBV, and ATR, along with helper routines for handling price series and missing values. The emphasis is on understanding indicator construction rather than treating indicator outputs as opaque signals.

The code illustrates calculation choices such as exponential smoothing, rolling windows, and initializing indicator values before enough observations are available. It offers no trading rules, backtest, or performance evidence, so it does not establish that these indicators predict returns or work well in any market. The supplied text is also incomplete: some implementation sections are omitted, and code shown across languages may not cover every function or edge case. Researchers should verify details such as initialization, zero denominators, and missing-data handling before relying on the outputs.

Key ideas

• The library derives several standard indicators directly from price and volume series.
• Moving averages use rolling-window or recursive smoothing calculations, depending on the indicator.
• Indicator outputs may be undefined at the beginning of a series while the required history accumulates.
• The examples teach calculation mechanics but provide no trading signals or evidence of profitability.
• The excerpt is incomplete, so implementations and edge cases require independent verification.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.