findMax.js

var obj = {
    fo1 : 5,
    fo2 : 3,
    fo3 : 10,
    fo4 : 3,
    fo5 : 4,
    fo6 : 4,
}

function getMax(object) {
    var values = Object.keys(object).map(function(key) {
        return {
            value: object[key],
            key: key
        }
    })

    const reducer = (accumulator, currentValue) => {
        if (accumulator.value > currentValue.value) {
            return accumulator
        }
        return currentValue
    }

    var max = values.reduce(reducer);

    return max
}

console.log(getMax(obj))