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			411 lines
		
	
	
		
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			Markdown
		
	
	
	
	
	
			
		
		
	
	
			411 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
 # Usage
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**Edit this Page** [](https://github.com/mermaid-js/mermaid/blob/develop/docs/usage.md)
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Mermaid is a Javascript tool that makes use of a markdown based syntax to render customizable diagrams, charts and visualizations.
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Diagrams can be re-rendered/modified by modifying their descriptions.
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### CDN
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[https://unpkg.com/mermaid/](https://unpkg.com/mermaid/)
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Please note that you can switch versions through the dropdown box at the top right.
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## Using mermaid
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For the majority of users, Using the [Live Editor](https://mermaid-js.github.io/mermaid-live-editor/) would be sufficient, however you may also opt to deploy mermaid as a dependency or using the [Mermaid API](./Setup.md).
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We have compiled some Video [Tutorials](./Tutorials.md) on how to use the mermaid Live Editor.
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**Installing and Hosting Mermaid on a Webpage**
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**Using the npm package**
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```
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1.You will need to install node v16, which would have npm.
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2. download yarn using npm.
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3. enter the following command:
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    yarn add mermaid
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4. At this point, you can add mermaid as a dev dependency using this command:
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    yarn add --dev mermaid
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5. Alternatively, you can also deploy mermaid using the script tag in an HTML file with mermaid diagram descriptions.
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    as is shown in the example below
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```
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**Hosting mermaid on a web page.**
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>Note:This topic explored in greater depth in the [User Guide for Beginners](./n00b-gettingStarted.md)
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The easiest way to integrate mermaid on a web page requires three elements:
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1. Inclusion of the mermaid address in the html page using a `script` tag, in the `src` section.Example:
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    ```html
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    <script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
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    ```
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2. The `mermaidAPI` call, in a separate `script` tag. Example:
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    ```html
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    <script>mermaid.initialize({startOnLoad:true});</script>
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    ```
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3. A graph definition, inside `<div>` tags labeled `class=mermaid`. Example:
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    ```html
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    <div class="mermaid">
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         graph LR
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          A --- B
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          B-->C[fa:fa-ban forbidden]
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          B-->D(fa:fa-spinner);
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    </div>
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    ```
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**Following these directions, mermaid starts at page load and (when the page has loaded) it will
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locate the graph definitions inside the `div` tags with `class="mermaid"` and return diagrams in SVG form, following given definitions.**
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## Simple full example:
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```html
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<!DOCTYPE html>
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<html lang="en">
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<head>
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  <meta charset="utf-8">
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</head>
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<body>
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  <div class="mermaid">
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  graph LR
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      A --- B
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      B-->C[fa:fa-ban forbidden]
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      B-->D(fa:fa-spinner);
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  </div>
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 <script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
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 <script>mermaid.initialize({startOnLoad:true});</script>
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</body>
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</html>
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```
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## Notes:
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An id attribute is also added to mermaid tags without one.
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Mermaid can load multiple diagrams, in the same page.
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> Try it out, save this code as HTML and load it using any browser.(Except Internet Explorer, please don't use Internet Explorer.)
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## Enabling Click Event and Tags in Nodes
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 A `securityLevel` configuration has to first be cleared, `securityLevel` sets the level of trust for the parsed diagrams and limits click functionality. This was introduce in version 8.2 as a security improvement, aimed at preventing malicious use.
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 **It is the site owner's responsibility to discriminate between trustworthy and untrustworthy user-bases and we encourage the use of discretion.**
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## securityLevel
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| Parameter     | Description                       | Type   | Required | Values                    |
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| ------------- | --------------------------------- | ------ | -------- | ------------------------- |
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| securityLevel | Level of trust for parsed diagram | String | Required | Strict, Loose, antiscript |
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Values:
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-   **strict**: (**default**) tags in text are encoded, click functionality is disabled
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-   **loose**: tags in text are allowed, click functionality is enabled
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-   **antiscript**: html tags in text are allowed, (only script element is removed), click functionality is enabled
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```note
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This changes the default behaviour of mermaid so that after upgrade to 8.2,unless the `securityLevel` is not changed, tags in flowcharts are encoded as tags and clicking is disabled.
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```
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**If you are taking responsibility for the diagram source security you can set the `securityLevel` to a value of your choosing . This allows clicks and tags are allowed.**
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**To change `securityLevel`, you have to call `mermaidAPI.initialize`:**
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```javascript
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mermaidAPI.initialize({
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    securityLevel: 'loose'
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});
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```
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### Labels out of bounds
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If you use dynamically loaded fonts that are loaded through CSS, such as Google fonts, mermaid should wait for the
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whole page to load (dom + assets, particularly the fonts file).
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```javascript
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$(document).load(function() {
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    mermaid.initialize();
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});
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```
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or
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```javascript
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$(document).ready(function() {
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    mermaid.initialize();
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});
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```
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Not doing so will most likely result in mermaid rendering graphs that have labels out of bounds. The default integration in mermaid uses the window.load event to start rendering.
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If your page has other fonts in its body those might be used instead of the mermaid font. Specifying the font in your styling is a workaround for this.
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```css
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div.mermaid {
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    font-family: 'trebuchet ms', verdana, arial;
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}
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```
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### Calling `mermaid.init`
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By default, `mermaid.init` will be called when the document is ready, finding all elements with
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`class="mermaid"`. If you are adding content after mermaid is loaded, or otherwise need
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finer-grained control of this behavior, you can call `init` yourself with:
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- a configuration object
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- some nodes, as
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  - a node
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  - an array-like of nodes
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  - or W3C selector that will find your nodes
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Example:
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```javascript
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mermaid.init({noteMargin: 10}, ".someOtherClass");
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```
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Or with no config object, and a jQuery selection:
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```javascript
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mermaid.init(undefined, $("#someId .yetAnotherClass"));
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```
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```warning
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This type of integration is deprecated. Instead the preferred way of handling more complex integration is to use the mermaidAPI instead.
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```
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## Usage with webpack
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mermaid fully supports webpack. Here is a [working demo](https://github.com/mermaidjs/mermaid-webpack-demo).
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## API usage
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The main idea of the API is to be able to call a render function with the graph definition as a string. The render function
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will render the graph and call a callback with the resulting svg code. With this approach it is up to the site creator to
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fetch the graph definition from the site (perhaps from a textarea), render it and place the graph somewhere in the site.
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The example below show an outline of how this could be used. The example just logs the resulting svg to the javascript console.
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```html
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<script src="mermaid.js"></script>
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<script>
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    mermaid.mermaidAPI.initialize({
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        startOnLoad:false
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    });
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    $(function(){
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        // Example of using the API
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        var element = document.querySelector("#graphDiv");
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        var insertSvg = function(svgCode, bindFunctions){
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            element.innerHTML = svgCode;
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        };
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        var graphDefinition = 'graph TB\na-->b';
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        var graph = mermaid.mermaidAPI.render('graphDiv', graphDefinition, insertSvg);
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    });
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</script>
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```
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### Binding events
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Sometimes the generated graph also has defined interactions like tooltip and click events. When using the API one must
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add those events after the graph has been inserted into the DOM.
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The example code below is an extract of what mermaid does when using the API. The example shows how it is possible to
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bind events to an svg when using the API for rendering.
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```javascript
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var insertSvg = function(svgCode, bindFunctions) {
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    element.innerHTML = svgCode;
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    if(typeof callback !== 'undefined'){
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        callback(id);
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    }
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    bindFunctions(element);
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};
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var id = 'theGraph';
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mermaidAPI.render(id,txt,insertSvg, element);
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```
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1. The graph is generated using the render call.
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2. After generation the render function calls the provided callback function, in this case it's called insertSvg.
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3. The callback function is called with two parameters, the svg code of the generated graph and a function. This function binds events to the svg **after** it is inserted into the DOM.
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4. Insert the svg code into the DOM for presentation.
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5. Call the binding function that binds the events.
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## Example of a marked renderer
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This is the renderer used for transforming the documentation from markdown to html with mermaid diagrams in the html.
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```javascript
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var renderer = new marked.Renderer();
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renderer.code = function (code, language) {
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    if(code.match(/^sequenceDiagram/)||code.match(/^graph/)){
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        return '<div class="mermaid">'+code+'</div>';
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    }
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    else{
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        return '<pre><code>'+code+'</code></pre>';
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    }
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};
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```
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Another example in coffeescript that also includes the mermaid script tag in the generated markup.
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```js
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marked = require 'marked'
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module.exports = (options) ->
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  hasMermaid = false
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  renderer = new marked.Renderer()
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  renderer.defaultCode = renderer.code
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  renderer.code = (code, language) ->
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    if language is 'mermaid'
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      html = ''
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      if not hasMermaid
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        hasMermaid = true
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        html += '<script src="'+options.mermaidPath+'"></script>'
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      html + '<div class="mermaid">'+code+'</div>'
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    else
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      @defaultCode(code, language)
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  renderer
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```
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## Advanced usage
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**Syntax validation without rendering (Work in Progress)**
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The **mermaid.parse(txt)** function validates graph definitions without rendering a graph. **[This function is still a work in progress](https://github.com/mermaid-js/mermaid/issues/1066), find alternatives below.**
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The function **mermaid.parse(txt)**, takes a text string as an argument and returns true if the definition follows mermaid's syntax and
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false if it does not. The parseError function will be called when the parse function returns false.
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When the parser encounters invalid syntax the **mermaid.parseError** function is called. It is possible to override this
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function in order to handle the error in an application-specific way.
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The code-example below in meta code illustrates how this could work:
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```javascript
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mermaid.parseError = function(err,hash){
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    displayErrorInGui(err);
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};
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var textFieldUpdated = function(){
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    var textStr = getTextFromFormField('code');
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    if(mermaid.parse(textStr)){
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        reRender(textStr)
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    }
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};
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bindEventHandler('change', 'code', textFieldUpdated);
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```
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**Alternative to mermaid.parse():**
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One effective and more future-proof method of validating your graph deinitions, is to paste and render them via the [Mermaid Live Editor](https://mermaid-js.github.io/mermaid-live-editor/). This will ensure that your code is compliant with the syntax of Mermaid's most recent version. 
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## Configuration
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Mermaid takes a number of options which lets you tweak the rendering of the diagrams. Currently there are three ways of
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setting the options in mermaid.
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1. Instantiation of the configuration using the initialize call
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2. *Using the global mermaid object* - **Deprecated**
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3. *using the global mermaid_config object* - **Deprecated**
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4. Instantiation of the configuration using the **mermaid.init** call- **Deprecated**
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The list above has two ways too many of doing this. Three are deprecated and will eventually be removed. The list of
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configuration objects are described [in the mermaidAPI documentation](Setup.md).
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## Using the `mermaidAPI.initialize`/`mermaid.initialize` call
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The future proof way of setting the configuration is by using the initialization call to mermaid or mermaidAPI depending
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on what kind of integration you use.
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```html
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<script src="../dist/mermaid.js"></script>
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<script>
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    var config = {
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        startOnLoad:true,
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        flowchart:{
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            useMaxWidth:false,
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            htmlLabels:true
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        }
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    };
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    mermaid.initialize(config);
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</script>
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```
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```tip
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This is the preferred way of configuring mermaid.
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```
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### The following methods are deprecated and are kept only for backwards compatibility.
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## Using the mermaid object
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Is it possible to set some configuration via the mermaid object. The two parameters that are supported using this
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approach are:
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* mermaid.startOnLoad
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* mermaid.htmlLabels
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```js
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mermaid.startOnLoad = true;
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```
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```warning
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This way of setting the configuration is deprecated. Instead the preferred way is to use the initialize method. This functionality is only kept for backwards compatibility.
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```
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## Using the mermaid_config
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It is possible to set some configuration via the mermaid object. The two parameters that are supported using this
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approach are:
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* mermaid_config.startOnLoad
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* mermaid_config.htmlLabels
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```javascript
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mermaid_config.startOnLoad = true;
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```
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```warning
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This way of setting the configuration is deprecated. Instead the preferred way is to use the initialize method. This functionality is only kept for backwards compatibility.
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```
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## Using the mermaid.init call
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To set some configuration via the mermaid object. The two parameters that are supported using this approach are:
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* mermaid_config.startOnLoad
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* mermaid_config.htmlLabels
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```
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mermaid_config.startOnLoad = true;
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```
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```warning
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This way of setting the configuration is deprecated. Instead the preferred way is to use the initialize method. This functionality is only kept for backwards compatibility.
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```
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