Custom Data Extension
Custom Data format allows extension authors to easily extend VS Code's HTML / CSS language support without having to write code.
The twoContribution Points for using custom data in an extension are:
contributes.html.customDatacontributes.css.customData
For example, by including this section in an extension'spackage.json:
{ "contributes": { "html": { "customData": ["./html.html-data.json"] }, "css": { "customData": ["./css.css-data.json"] } }}VS Code will load the HTML/CSS entities defined in both files and provide language support such as auto-completion and hover information for those entities.
You can find thecustom-data-sample atmicrosoft/vscode-extension-samples.
12/10/2025