@tanstack/markdown/dist/extensions/streaming.js

A tiny, fast, deterministic Markdown renderer for blogs and documentation.

export function streamingMarkdownExtension() {
    return {
        name: 'streaming',
        transformDocument(document) {
            const children = trimTrailingPlaceholder(document.children);
            return children === document.children ? document : { ...document, children };
        },
    };
}
function trimTrailingPlaceholder(children) {
    const last = children.at(-1);
    if (!last)
        return children;
    const trimmed = trimBlock(last);
    if (trimmed === last)
        return children;
    if (!trimmed)
        return children.slice(0, -1);
    return [...children.slice(0, -1), trimmed];
}
function trimBlock(node) {
    if (node.type === 'heading' && node.children.length === 0)
        return undefined;
    if (node.type === 'blockquote') {
        const children = trimTrailingPlaceholder(node.children);
        if (children.length === 0)
            return undefined;
        return children === node.children ? node : { ...node, children };
    }
    if (node.type !== 'list')
        return node;
    const last = node.items.at(-1);
    if (!last)
        return undefined;
    const item = trimListItem(last);
    if (item === last)
        return node;
    const items = item ? [...node.items.slice(0, -1), item] : node.items.slice(0, -1);
    return items.length === 0 ? undefined : { ...node, items };
}
function trimListItem(item) {
    const children = trimTrailingPlaceholder(item.children);
    if (children.length === 0)
        return undefined;
    return children === item.children ? item : { ...item, children };
}