Quick Start

dxScript is a JavaScript-based language for creating custom technical analysis indicators with built-in support for time series, historical lookback, and technical analysis functions.

Script Structure

Every indicator has two sections: the init section that runs once, and the onTick function that runs for each bar.

// Init section — runs once
const length = input.double("length", 20);

// onTick function — runs for each tick
function onTick() {
    const sma = ta.sma(close, length);
    spline(sma, {title: "SMA"});
}

Init Section

All code outside onTick() executes once when the indicator is created, before processing any market data.

Use for:

• Declaring input parameters
• Defining constants
• Defining helper functions

Example

// Input parameters
const length = input.double("length", 20, {min: 1, max: 200});
const source = input.source("source", close);

// Constants
const OVERBOUGHT = 70;
const OVERSOLD = 30;

// Helper functions
function inRange(value, min, max) {
    return value >= min && value <= max;
}

Caveats

• Price data (open, high, low, close, etc.) is not available.

onTick Function

The onTick() function is called for each bar (candle) in the data.

Use for:

• Accessing market data (open, high, low, close, volume)
• Creating time series with ts()
• Performing calculations
• Producing outputs with spline()

Example

function onTick() {
    const sma = ta.sma(close, length);
    const signal = ts(close > sma ? 1 : -1);

    spline(sma, {title: "SMA"});
    spline(signal, {title: "Signal"});
}

Key Concepts

Inputs

Declare configurable parameters in the init section:

const length = input.double("length", 20, {min: 1, max: 200});
const useEma = input.bool("useEma", true);
const source = input.source("source", close);

Time Series

Store calculated values with history access:

function onTick() {
    const sma = ta.sma(close, length);  // ta.* returns series
    const prev = sma[1];                 // previous bar value
    const old = sma[10];                 // 10 bars ago
}

Outputs

Plot values on the chart:

function onTick() {
    spline(close, {title: "Price", color: color.BLUE});
}

Complete Example

Moving Average Crossover indicator:

// INIT
const length = input.double("length", 20, {min: 1, max: 200});

// TICK
function onTick() {
    const sma = ta.sma(close, length);
    const trend = close > sma ? color.GREEN : color.RED;

    spline(sma, {title: "SMA"});
    spline(close, {title: "Price", color: trend});
}

Next Steps

• Explore Time Series in depth
• Understand Real-time Behavior
• Learn about the Runtime Environment
• Browse the Language Reference