Find all the parents of each element (hierarchy)

hierarchy.js

var tree = [
    { "roleName" : "Humans", "roleId" : "role2", "children" : []},
    { "roleName" : "Trees", "roleId" : "role2", "children" : []},
    { "roleName" : "Animals", "roleId" : "role2", "children" : [
        { "roleName" : "Cats", "roleId" : "role11", "children" : []},
        { "roleName" : "Lions", "roleId" : "role11", "children" : []},
        { "roleName" : "Dogs", "roleId" : "role11", "children" : [
            { "roleName" : "Terrier", "roleId" : "role11", "children" : []},
            { "roleName" : "Bulldog", "roleId" : "role11", "children" : []},
            { "roleName" : "Cocker", "roleId" : "role11", "children" : []},
        ]}
    ]},
    { "roleName" : "Cars", "roleId" : "role2", "children" : []}
];// using the original data from your question

var index = {};

function buildIndex(root, children) {
    for(var i in children) {
        index[children[i].roleName] = root;
        buildIndex(children[i].roleName, children[i].children);
    }
}

buildIndex(false, tree);// first parameter evaluating to false means "no root"

console.log(index);

function getPath(leaf) {
    return index[leaf] ? getPath(index[leaf]).concat([leaf]) : [leaf];
}

document.body.innerHTML = getPath("Cocker").join(" / ");// show the path to Cocker