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Beginner5 min read
This guide walks you through creating your very first indicator in kScript. We’ll build an off-chart indicator that plots the difference between two EMAs as bars.

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Anatomy of a kScript

Every kScript has three main parts:
1

Definition

Define the name, title, and placement of your indicator
2

Logic

Calculate the data that will be plotted
3

Plot

Visualize the data

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Step 1: Basic Script Structure

We’ll build an off-chart indicator that plots the difference between two EMAs as bars. Every kScript v2 starts with a compiler annotation //@version=2 followed by a define() function that tells the platform what your script does and where to display it. 
//@version=2

// definition
define(title="EMA Difference", position="offchart", axis=true, customTitle="($fastPeriod, $slowPeriod)");

// logic

// plot
Explanation:
  • //@version=2 - Required compiler annotation that tells kScript to use version 2 syntax and features
  • "EMA Difference" - The display name in the UI
  • "offchart" - Shows the indicator in a separate panel below the main chart
  • true - Creates an independent Y-axis for better scaling
  • "($fastPeriod, $slowPeriod)" - Adds input values to the title, so it displays as “EMA Difference (7, 14)“

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Step 2: Get the Data

To plot anything, we first need data. In kScript, that starts with subscribing to a data source. The ohlcv() function gives us OHLCV (trade data). For this example, we’ll focus on close prices. 
//@version=2

// definition
define(title="EMA Difference", position="offchart", axis=true, customTitle="($fastPeriod, $slowPeriod)");

// logic
timeseries ohlcvDataSet = ohlcv(symbol=currentSymbol, exchange=currentExchange);

// plot
Data source explained:
  • timeseries - A special type for time-series data. All other types can be declared using var
  • ohlcv(...) - Gets OHLCV data of the current chart
  • currentSymbol - Uses the currently selected trading pair
  • currentExchange - Uses the currently selected exchange
Curious about the shape of this dataset? Click Apply, save the script, then hit the Data icon at the top to inspect it.

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Step 3: Build the Logic

Now let’s calculate our EMAs. The standard library includes an ema() function. We’ll calculate a fast EMA (7 periods) and slow EMA (14 periods), then find their difference. 
//@version=2

// definition
define(title="EMA Difference", position="offchart", axis=true, customTitle="($fastPeriod, $slowPeriod)");

// logic
timeseries ohlcvDataSet = ohlcv(symbol=currentSymbol, exchange=currentExchange);

var fastEma = ema(source=ohlcvDataSet, period=7, priceIndex=4); // dataset, period, close column (4)
var slowEma = ema(source=ohlcvDataSet, period=14, priceIndex=4); // dataset, period, close column (4)

// Alternatively, you can use the .close property for cleaner syntax
// var fastEma = ema(source=ohlcvDataSet.close, period=7);
// var slowEma = ema(source=ohlcvDataSet.close, period=14);

var difference = fastEma - slowEma;

// plot
EMA calculations:
  • ema(ohlcvDataSet, 7, 4) - Fast EMA with 7 periods using close price (column 4)
  • ema(ohlcvDataSet, 14, 4) - Slow EMA with 14 periods using close price (column 4)
  • fastEma - slowEma - Calculate the difference between the two EMAs
You can inspect the difference dataset to confirm calculations by using the Data inspection feature.

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Step 4: Plot the Data

Now let’s plot the difference as bars using the plotBar() function. We’ll use green bars for positive values and red bars for negative values. 
//@version=2

// definition
define(title="EMA Difference", position="offchart", axis=true, customTitle="($fastPeriod, $slowPeriod)");

// logic
timeseries ohlcvDataSet = ohlcv(symbol=currentSymbol, exchange=currentExchange);

var fastEma = ema(source=ohlcvDataSet.close, period=7); // dataset, period, close column
var slowEma = ema(source=ohlcvDataSet.close, period=14); // dataset, period, close column

var difference = fastEma - slowEma;

var colorIndex = difference > 0 ? 0 : 1;

// plot
plotBar(value=difference, width=1, colors=["green", "red"], colorIndex=colorIndex, label=["EMA Difference"], desc=["Fast EMA - Slow EMA"]);
plotBar parameters:
  • difference - The EMA difference data series to plot as bars
  • ["green", "red"] - Color array for positive/negative bars
  • colorIndex - Index to select specific color from colors array (0 for green, 1 for red)
  • 1 - Bar width
EMA Difference indicator

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Step 5: Add User Inputs

Hardcoding values isn’t very flexible. Instead, let’s allow users to set the periods via inputs using the input() function. This makes your indicator customizable. 
//@version=2

// definition
define(title="EMA Difference", position="offchart", axis=true, customTitle="($fastPeriod, $slowPeriod)");

var fastPeriod = input(name="fastPeriod", type="number", defaultValue=7, label="Fast Period");
var slowPeriod = input(name="slowPeriod", type="number", defaultValue=14, label="Slow Period");

// logic
timeseries ohlcvDataSet = ohlcv(symbol=currentSymbol, exchange=currentExchange);

var fastEma = ema(source=ohlcvDataSet.close, period=fastPeriod);
var slowEma = ema(source=ohlcvDataSet.close, period=slowPeriod);

var difference = fastEma - slowEma;

var colorIndex = difference > 0 ? 0 : 1;

// plot
plotBar(value=difference, width=1, colors=["green", "red"], colorIndex=colorIndex, label=["EMA Difference"], desc=["Fast EMA - Slow EMA"]);
Input parameters:
  • fastPeriod - Key for the input (used in code)
  • "number" - Input type (number)
  • 7 - Default value
  • "Fast Period" - Label shown to users
We use var instead of timeseries because user inputs are scalar values, not time series.
If you want to include the user settings in the indicator title, you can change the definition like this: define("EMA Difference", "offchart", true, "($fastPeriod, $slowPeriod)"); The title will then read as “EMA Difference (7, 14)”.

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Final Script

Here’s your complete EMA Difference indicator script: 
//@version=2

// definition
define(title="EMA Difference", position="offchart", axis=true, customTitle="($fastPeriod, $slowPeriod)");

var fastPeriod = input(name="fastPeriod", type="number", defaultValue=7, label="Fast Period");
var slowPeriod = input(name="slowPeriod", type="number", defaultValue=14, label="Slow Period");

// logic
timeseries ohlcvDataSet = ohlcv(symbol=currentSymbol, exchange=currentExchange);

var fastEma = ema(source=ohlcvDataSet.close, period=fastPeriod);
var slowEma = ema(source=ohlcvDataSet.close, period=slowPeriod);

var difference = fastEma - slowEma;

var colorIndex = difference > 0 ? 0 : 1;

// plot
plotBar(value=difference, width=1, colors=["green", "red"], colorIndex=colorIndex, label=["EMA Difference"], desc=["Fast EMA - Slow EMA"]);
Congratulations! You’ve built your first kScript indicator. Try experimenting with different functions, plots, and inputs next.

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What’s Next?

Moving Averages

Learn about SMA, EMA, WMA, and other moving average functions

Core Variables

Understand data types and built-in variables in kScript

Advanced Plotting

Master visualization techniques and chart styling options