> For the complete documentation index, see [llms.txt](https://sway-technologies.gitbook.io/sway-charts-pro-scripts-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sway-technologies.gitbook.io/sway-charts-pro-scripts-documentation/sway-charts-pro-user-defined-indicators/introduction.md).

# Introduction

It's easy to write your own indicators for Figaro charts. User-defined indicators (UDIs) are just Javascript. You can use any editor of your choice, from Notepad to Eclipse or Visual Studio. A UDI typically has only two simple functions, and you can use all the features of the Javascript language. For large complex projects, you can even use an environment such as Typescript or Coffeescript which compiles to produce Javascript.

 

UDIs can do all the same things as the built-in indicators:

 

·      Plot values in a variety of styles, such as lines, points, histograms, channels, and candles

·      Create drawings on the chart, such as rectangles and lines

·      Create event markers

·      Create bar highlights (changing the colours of specific candles on the chart)

 

UDIs are web workers and have access to all the standard features of the browser's Javascript environment. For example, they can set timers, and they can read external data such as an economic calendar or trading signals, using XMLHttpRequest or [web sockets](https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API).

 

You can debug your UDI using the features built into your browser, such as Chrome's Developer Tools.


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