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When mermaid starts, configuration is extracted to determine a configuration to be used for a diagram. There are 3 sources for configuration:

  • The default configuration
  • Overrides at the site level are set by the initialize call, and will be applied to all diagrams in the site/app. The term for this is the siteConfig.
  • Directives - diagram authors can update select configuration parameters directly in the diagram code via directives. These are applied to the render config.

The render config is configuration that is used when rendering by applying these configurations.

Theme configuration

Starting mermaid

	Site->>mermaid: initialize
	Site->>mermaid: content loaded
	mermaid->>mermaidAPI: init


The initialize call is applied only once. It is called by the site integrator in order to override the default configuration at a site level.


This method resets the configuration for a diagram to the overall site configuration, which is the configuration provided by the site integrator. Before each rendering of a diagram, reset is called at the very beginning.