var str = 'style';

var obj = {

    'style-2': true,

    'style-3': false,

    'style-4': true,

}

var arr = ['style-5', 'style-6']

​

const isArray = (value) => Array.isArray(value)

const isUndefined = (value) => typeof value === "undefined"

const isString = (value) => typeof value === "string"

const isNumber = (value) => !Number.isNaN(value) && typeof value === "number"

const isObject = (value) => !isArray(value) && value !== null && typeof value === "object"

​

function composeClass(...values) {

    if (!values.length) {

        return

    }

​

    const classNameStack = []

​

    for (const value of values) {

        switch (true) {

            case !value: {

                continue

            }

            case isString(value):

            case isNumber(value): {

                classNameStack.push(value)

                continue

            }

            case isArray(value) && value.length > 0: {

                const valueFromArray = Reflect.apply(composeClass, undefined, value)

​

                if (!isUndefined(valueFromArray)) {

                    classNameStack.push(valueFromArray)

                }

                continue

            }

            case isObject(value): {

                for (const key in value) {

                    if (value[key]) {

                        classNameStack.push(key)

                    }

                }

                continue

            }

        }

    }

​

    return classNameStack.length > 0 ? classNameStack.join(" ") : undefined

}