Get a selector parent selector with csstree (an issue https://twitter.com/peterbe/status/1079854825880326144)

get-selector-parent.js

const cssTree = require("css-tree@1.0.0-alpha.29");

function getSelectorParent(selector) {
    const selectorAst = cssTree.parse(selector, { context: 'selector' });

    // solution #1
    selectorAst.children.prevUntil(selectorAst.children.tail, (node, item, list) => {
        list.remove(item);
        return node.type === 'Combinator' || node.type === 'WhiteSpace';
    });
    
    // solution #2
//     let item;
//     while (item = selectorAst.children.pop()) {
//         const node = item.data;
//         if (node.type === 'Combinator' || node.type === 'WhiteSpace') {
//             break;
//         }
//     }
    
    return cssTree.generate(selectorAst);
}

[ '.foo .bar', '.foo', 'div>p' ].forEach(selector => {
    console.log(`[${selector}] -parent-> [${getSelectorParent(selector)}]`);
});