const isMap = (val) =>
    toTypeString(val) === '[object Map]'
const objectToString =
    Object.prototype.toString
const toTypeString = (value) =>
    objectToString.call(value)

function isMap2(val) {
    return val instanceof Map
}

function isMap3(val) {
    return val.constructor.name === "Map"
}

function isMap4(val) {
    return !!val && (val)[Symbol.toStringTag] === 'Map'
}

var mapLike = new Map();