How can i roll up the child values to the parent even if i switch the positions?

So what i want to acheive is that, i will add the child selector values to the parent selector. so these are just the two selectors i’m using to test, they can be more and different too. When i switch the postions of the child and parent the algorithm doesn’t seem to work.. is there a way to fix this?

this code works as expected

const ecommerceObj = {
    'header#section-header > div > div.Header__FlexItem.Header__FlexItem--fill.hidden-phone > nav > ul > li:nth-child(6) > a':
        {
            revenue: 4,
            sessions: 3,
        },
    'header#section-header > div > div.Header__FlexItem.Header__FlexItem--fill.hidden-phone > nav > ul > li:nth-child(6) > a > span':
        {
            revenue: 6,
            sessions: 8,
        },
};

function generateRollUpValues(ecommerceObj) {
    const getParent = (str) => {
        const idx = String(str).lastIndexOf(' > ');
        if (idx > 0) {
            return str.substr(0, idx);
        }
        return false;
    };
    const rollup = {};
    const rev = [];
    const keys = Object.keys(ecommerceObj);
    // eslint-disable-next-line no-plusplus
    for (let i = 0; i < keys.length; i++) {
        rev.push(keys[i]);
    }
    for (let t = rev.length - 1; t >= 0; t -= 1) {
        const key = rev[t];
        const current = ecommerceObj[key];
        const p = getParent(key);
        // console.log(key + ' -> ' + p);
        if (p && rollup[p] === undefined) {
            rollup[p] = {
                revenue: 0,
                sessions: 0,
            };
        }
        if (rollup[key] != undefined) {
            ecommerceObj[key].revenue += rollup[key].revenue;
            ecommerceObj[key].sessions += rollup[key].sessions;
        }
        if (p) {
            rollup[p].revenue += ecommerceObj[key].revenue;
            rollup[p].sessions += ecommerceObj[key].sessions;
        }
    }

    return ecommerceObj;
}
console.log(generateRollUpValues(ecommerceObj));

but this doesn’t work

const ecommerceObj = {
    'header#section-header > div > div.Header__FlexItem.Header__FlexItem--fill.hidden-phone > nav > ul > li:nth-child(6) > a > span':
        {
            revenue: 6,
            sessions: 8,
        },
    'header#section-header > div > div.Header__FlexItem.Header__FlexItem--fill.hidden-phone > nav > ul > li:nth-child(6) > a':
        {
            revenue: 4,
            sessions: 3,
        },
};

>Solution :

function generateRollUpValues(ecommerceObj) {
    const getParent = (str) => {
        const idx = String(str).lastIndexOf(' > ');
        if (idx > 0) {
            return str.substr(0, idx);
        }
        return false;
    };
    const rollup = {};
    const rev = [];
    const keys = Object.keys(ecommerceObj);
    
    // eslint-disable-next-line no-plusplus
    
    keys.forEach(key => {
        rev.push(key);
    });
    rev.sort();
    for (let t = rev.length - 1; t >= 0; t -= 1) {
        const key = rev[t];
        const current = ecommerceObj[key];
        const parent = getParent(key);
        // console.log(key + ' -> ' + parent);
        if (parent && rollup[parent] === undefined) {
            rollup[parent] = {
                revenue: 0,
                sessions: 0,
            };
        }
        if (rollup[key] != undefined) {
            ecommerceObj[key].revenue += rollup[key].revenue;
            ecommerceObj[key].sessions += rollup[key].sessions;
        }
        if (parent) {
            rollup[parent].revenue += ecommerceObj[key].revenue;
            rollup[parent].sessions += ecommerceObj[key].sessions;
        }
    }

    return ecommerceObj;
}