Use the WireViz: Preview button on the editor toolbar (right of tabs),
or using the default F8 shortcut key.
Once the preview is open, it will refresh every time you save the file.
This behaviour can be disabled by setting "wireviz.refreshPreviewOnSave": false.
Configuration
Open VSCode settings, filter for WireViz. You'll find settings for command-line args to specify, and a couple extension-specific settings.
Troubleshooting
Please make sure you're running WireViz 0.4 or above. Their new command line options are incompatible with 0.3 and below.
If you are running into issues after upgrading to WireViz 0.4, try running WireViz against your input file from the terminal:
If it works on the terminal but not through the extension, please report it as a new issue here.
If the terminal also throws an error, please downgrade WireViz to 0.3, and downgrade this extension to 1.0.x, and wait until they fix it.
