经常使用的js util函数

判断数据类型

function type(target) {
  let ret = typeof (target);
  const TYPE_MAP = {
    "[object Array]": "array",
    "[object Object]": "object",
    "[object Number]": "number",
    "[object Boolean]": "boolean",
    "[object String]": 'string'
  };

  if (target === null) {
    return 'null';
  } else if (ret == "object") {
    let str = Object.prototype.toString.call(target);
    return TYPE_MAP[str];
  } else {
    return ret;
  }
}

生成指定范围随机数

const RandomNum = (min, max) => {
	return Math.floor(Math.random() * (max - min + 1)) + min;
}

数组乱序

function arrScrambling(arr) {
  let array = arr;
  let index = array.length;
  while (index) {
    index -= 1;
    let randomIndex = Math.floor(Math.random() * index);
    let middleware = array[index];
    array[index] = array[randomIndex];
    array[randomIndex] = middleware
  }
  return array
}

数组交集

const similarity = (arr1, arr2) => arr1.filter(v => arr2.includes(v));

数组中某元素出现的次数

function countOccurrences(arr, value) {
    return arr.reduce((a, v) => v === value ? a + 1 : a + 0, 0);
}

加法

function add(arg1, arg2) {
  let r1, r2, m;
  try { r1 = arg1.toString().split(".")[1].length } catch (e) { r1 = 0 }
  try { r2 = arg2.toString().split(".")[1].length } catch (e) { r2 = 0 }
  m = Math.pow(10, Math.max(r1, r2));
  return (arg1 * m + arg2 * m) / m
}

减法

function sub(arg1, arg2) {
  let r1, r2, m, n;
  try { r1 = arg1.toString().split(".")[1].length } catch (e) { r1 = 0 }
  try { r2 = arg2.toString().split(".")[1].length } catch (e) { r2 = 0 }
  m = Math.pow(10, Math.max(r1, r2));
  n = (r1 >= r2) ? r1 : r2;
  return Number(((arg1 * m - arg2 * m) / m).toFixed(n));
}

乘法

function mcl(num1, num2) {
  let m = 0, s1 = num1.toString(), s2 = num2.toString();
  try { m += s1.split(".")[1].length } catch (e) { }
  try { m += s2.split(".")[1].length } catch (e) { }
  return Number(s1.replace(".", "")) * Number(s2.replace(".", "")) / Math.pow(10, m);
}

除法

function division(num1, num2) {
  let t1, t2, r1, r2;
  try {
    t1 = num1.toString().split('.')[1].length;
  } catch (e) {
    t1 = 0;
  }
  try {
    t2 = num2.toString().split(".")[1].length;
  } catch (e) {
    t2 = 0;
  }
  r1 = Number(num1.toString().replace(".", ""));
  r2 = Number(num2.toString().replace(".", ""));
  return (r1 / r2) * Math.pow(10, t2 - t1);
}

格式化时间

function formatTime(number, format) {

  var formateArr = ['Y', 'M', 'D', 'h', 'm', 's'];
  var returnArr = [];

  var date = new Date(number * 1000);
  returnArr.push(date.getFullYear());
  returnArr.push(formatNumber(date.getMonth() + 1));
  returnArr.push(formatNumber(date.getDate()));

  returnArr.push(formatNumber(date.getHours()));
  returnArr.push(formatNumber(date.getMinutes()));
  returnArr.push(formatNumber(date.getSeconds()));

  for (var i in returnArr) {
    format = format.replace(formateArr[i], returnArr[i]);
  }
  return format;
}