# 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. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://sway-technologies.gitbook.io/sway-charts-pro-scripts-documentation/sway-charts-pro-user-defined-indicators/introduction.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.