Deep cloning functionality for JS

deepClone.js

function cloneObject(input) {
    if (isPrimitive(input)) {
        return input;
    }

    if (Array.isArray(input)) {
        return input.map((item)=>{return cloneObject(item);});
    }

    const clone = {};
    for (let prop in input) {
        if (input[prop] instanceof Date) {
            clone[prop] = new Date(input[prop].getTime());
        } else if(Array.isArray(input[prop])) {
            clone[prop] = input[prop].map((item)=>{return cloneObject(item);});
        } else if (input[prop] != null && typeof(input[prop]) == "object") {
            clone[prop] = cloneObject(input[prop]);
        } else {
            clone[prop] = input[prop];
        }
    }
    return clone;
}

function isPrimitive(test) {
    return (test !== Object(test));
}