Concatenates N arrays without dupplications

concatWithoutDups.js

/**
 * Concatenates N arrays without dups.
 * If an array's item is an Object, compare by `value`
 * @param {*} k
 */
export const concatWithoutDups = (...key) => {
    const result = (...args) => {
        const newArr = [],
            existingObj = {};

        for( let arr of args ) {
            for( let item of arr ) {
                // if current item is an object which has yet to be added to the new array
                if( isObject(item) ){
                    if( !existingObj[item[key]] || !key ){
                        newArr.push(item)
                        existingObj[item[key]] = 1
                    }
                }

                // if current item is not an object and is not in the new array
                else if( !newArr.includes(item) )
                    newArr.push(item)
            }
        }

        return newArr
    }

    if( key.length > 1 ){
        let args = key;
        key = null;
        return result(...args)
    }
    else
        key = key[0]

    return result
}

Without caring about duplicate objects

concatWithoutDups([1,"a"], ["b",1,"a", {value:1}], [{value:1}, 7], [{value:2}])

Skip objects with same key

concatWithoutDups('value')([1,"a"], ["b",1,"a", {value:1}], [{value:1}, 7], [{value:2}])