const ThousandNum = num => num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");

const money = ThousandNum(20190214);

// money => "20,190,214"

const num1 = ~~ 1.69;

const num2 = 1.69 | 0;

const num3 = 1.69 >> 0;

// num1 num2 num3 => 1 1 1

const num1 = +null;

const num2 = +"";

const num3 = +false;

const num4 = +"169";

// num1 num2 num3 num4 => 0 0 0 169

const RoundNum = (num, decimal) => Math.round(num * 10 ** decimal) / 10 ** decimal;

const num = RoundNum(1.69, 1);

// num => 1.7

const arr = [0, 1, 2];

const min = Math.min(...arr);

const max = Math.max(...arr);

// min max => 0 2

const obj = {};

const flag = DataType(obj, "object") && !Object.keys(obj).length;

// flag => true

function DataType(tgt, type) {

    const dataType = Object.prototype.toString.call(tgt).replace(/\[object (\w+)\]/, "$1").toLowerCase();

    return type ? dataType === type : dataType;

}

DataType("liner"); // "string"

DataType(2020630); // "number"

DataType(true); // "boolean"

DataType([], "array"); // true

DataType({}, "array"); // false

const _arr = [0, 1, 2];

const arr = [..._arr];

// arr => [0, 1, 2]

const arr1 = [0, 1, 2];

const arr2 = [3, 4, 5];

const arr = [...arr1, ...arr2];

// arr => [0, 1, 2, 3, 4, 5];

const arr = [...new Set([0, 1, 1, null, null])];

// arr => [0, 1, null]

const arr = [0, 1, 2];

arr.length = 2;

// arr => [0, 1]

let a = 0;

let b = 1;

[a, b] = [b, a];

// a b => 1 0

const _obj = { a: 0, b: 1, c: 2 }; // 以下方法任选一种(本人偏爱第一种，简单明了，与克隆数组几乎一样)

const obj = { ..._obj };

const obj = JSON.parse(JSON.stringify(_obj));

// obj => { a: 0, b: 1, c: 2 }

const obj1 = { a: 0, b: 1, c: 2 };

const obj2 = { c: 3, d: 4, e: 5 };

const obj = { ...obj1, ...obj2 };

// obj => { a: 0, b: 1, c: 3, d: 4, e: 5 }