remark-css-selectors/lib/components/tokenizers/inlineAttrTokenizer.js

Adding class and id attribute to AST tree (not standard markdown syntax)

function locateMention(value, fromIndex) {
    return value.indexOf('{', fromIndex)
}

tokenizeInlineAttr.notInLink = true
tokenizeInlineAttr.locator = locateMention

function tokenizeInlineAttr(eat, value, silent) {

    let match = /^{(\.|#)((?:\w|-|\s)+)}/.exec(value)
    if (match) {
        if (silent) {
            return true
        }
        return eat(match[0])({
            type: (match[1] === "#") ? 'attrId' : 'attrClass',
            value: match[2]
        })
    }
}

export default tokenizeInlineAttr;