SOURCE

function judgeType(value) {
    if (value == null) {
        return value + "";
    }
    let str = (typeof value === "object" || typeof value === "function" ? Object.prototype.toString.call(value) : typeof value)
    str = str.replace(/(\[object )|\]/g, '').toLowerCase()
    return str
}

function isFunction(value) {
    return judgeType(value) === 'function'
}

function isDate(date) {
    return judgeType(date) === 'date'
}