export default function plugin() { return transformer; function transformer(tree) { function traverse(node) { if (node.type === "image") { node.data = node.data || {}; node.data.hProperties = node.data.hProperties || {}; node.data.hProperties.id = "test"; node.data.hProperties.width = "300"; node.data.hProperties.widths = [300,600]; node.data.hProperties.sizes = "(min-width: 600px) 600w, 300w"; } if (node.children) { node.children.forEach(traverse); } } traverse(tree); } }