项目中由⼀个组件，向上找到所有的指定组件

export function findComponentDownward (context, componentName) {
const childrens = context.$children;
let children = null;

if (childrens.length) {
    for (const child of childrens) {
        const name = child.$options.name;
        if (name === componentName) {
            children = child;
            break;
        } else {
            children = findComponentDownward(child, componentName);
            if (children) break;
        }
    }
}
return children;