js一些小功能（持续更新）

1. 阻止浏览器回退

/**
 * 阻止浏览器回退ts
 * 传的data是因为ts语法规则不允许给string赋值null
 * js将data改成null即可
 */
const holdBack = (data: any) => {
  //阻止浏览器回退
  if (window.history && window.history.pushState) {
    window.history.pushState(null, data, document.URL);
    window.addEventListener('popstate', () => {
      window.history.pushState(null, data, document.URL);
    }, false);
  }
}

1. 生成6位随机字符串

/**
 * 生成6位随机字符串
 * @returns 
 */
const randomCode = () => {
  let character = ''
  let len = 6; // 选择的生成的位数
  let code = '0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASFGHJKLZXCVBNM'
  let maxPos = code.length;
  for (let i = 0; i < len; i++) {
    character += code.charAt(Math.floor(Math.random() * maxPos))
  }
  return character
}

1. RegExp模糊查询

/**
 * RegExp模糊查询
 * @returns 
 */
var list = ['nai','43q','5xn']
var keyWord = 'n'
var arr = []
var reg = new RegExp(keyWord)

for(var i = 0; i < list.length; i++) {
    if(list[i].match(reg)) {
         arr.push(list[i]);
    }
}
console.log(arr)

1. 两个数组对象找不同

/**
 * 两个数组对象找不同
 * @returns 
 */
var arr1 = [ { id: 1, name: '张三' }, { id: 2, name: '张四' }, { id: 3, name: '张五' }, { id: 4, name: '张六' } ];
var arr2 = [ { id: 1, name: '李三' }, { id: 2, name: '李四' }, { id: 3, name: '李五' }, { id: 4, name: '李六' }, { id: 5, name: '张六' } ];
var result = [];
for (var i = 0; i < arr2.length; i++) {
  var obj = arr2[i];
  var num = obj.id;
  var isExist = false;
  for (var j = 0; j < arr1.length; j++) {
    var aj = arr1[j];
    var n = aj.id;
    if (n == num) {
      isExist = true;
      break;
    }
  }
  if (!isExist) {
    result.push(obj);
  }
}
console.log(result);

1. 两个数组找不同

/**
 * 两个数组找不同
 * @returns 
 */
let arr1 = ['a', 'b', 'c']
let arr2 = ['a', 'b', 'c', 'd', 'e']
let arr3 = []
for (let i = 0; i < arr2.length; i++) {
  let obj = arr2[i]
  let isExist = false;
  for (let k = 0; k < arr1.length; k++) {
    if (arr2[i] === arr1[k]) {
      console.log('数据',k,arr2[i] === arr1[k])
      isExist = true;
      break
    }
  }
  if (!isExist) {
    console.log('执行我',i)
    arr3.push(obj);
  }
}
console.log(arr3)

1. 删除数组中指定值

/**
 * 删除数组中指定值
 * @returns 
 */
let arr1 = ['a', 'b', 'c', 'd', 'e']
for (const index in arr1) {
  if (arr1[index] === 'a') {
    console.log('删除',arr1[index],index)
    arr1.splice(index, 1)
  }
}

1. formData上传名称问题

/**
 * 修改上传文件的filename
 * @returns 
 */
Content-Disposition: form-data; name="signImg"; filename="我是名称"
formData.append('signImg', blob, '我是名称.png');

1. 下载blob文件

/**
 * 下载blob文件
 * @returns 
 */
function saveContent(content, fileName) {
  let aTag = document.createElement('a');
  aTag.setAttribute('download', fileName);
  let blob = new Blob([content], { type: "" });
  aTag.setAttribute('href', URL.createObjectURL(blob));
  document.body.appendChild(aTag);
  aTag.click();
  document.body.removeChild(aTag);
}
//需要注意，要设置请求responseType:'blob'

1. 正则替换关闭网页

/**
 * 正则替换关闭网页
 * @returns 
 */
var str = "http://192.168.10.254:20000/talk/#/middle-skip?meetingId=735073733^&userId=12345678^&appId=appId123456789^&url=http://192.168.10.254:22000/butt^&fydm=法院代码^&userName=李志祥^&source=tdh"
str.replace(/\&/g,"^&")
console.log(str)
function ClosePage() {
  open(location, '_self').close();
}

1. 测试上传文件

/**
 * 测试上传文件
 * @returns 
 */
const loadFile = function (name) { // name为文件所在位置
  let xhr = new XMLHttpRequest(),
      okStatus = document.location.protocol === "file:" ? 0 : 200;
  xhr.open('GET', 'C:\\Users\\12456\\Desktop\\图片\\前端转换的测试.pdf', true);
  xhr.overrideMimeType("text/html;charset=utf-8");//默认为utf-8
  xhr.send(null);
  console.log(xhr.status === okStatus ? xhr.responseText : null)
}

1. 筛选数字

/**
 * 筛选出数字
 * @returns 
 */
let str = '123456aaas45sd456asdaqweqw'
console.log(str.replace(/[^-](\d)-|[^\d]/ig, ''))

1. 扁平化数组（打印对象）

/**
 * 扁平化数组
 * @returns 
 */
let arr = [
  1,
  [2,3,4,5,6,[7,8,[9,[10,11]]]],
  12,13
]
console.log('格式化之前')
console.log(arr)
console.log('格式化之前')
console.log('---------分割线---------')
console.log('格式化之后')
console.log([...new Set(arr.flat(Infinity))].sort((a,b) => a-b))
console.log('格式化之后')


/**
 * js查询对象
 * @returns 
 */
let obj = {
  userId: '12345678',
  meetingId: '795576763',
  fydm: 'jsx4122',
  appId: 'a1a12'
}
console.log(obj.meetingId)

1. 数组对象合并去重

/**
 * 数组对象合并去重
 * @returns 
 */
let arr1 = [
  { id: 1, name: "aaa" },
  { id: 2, name: "bbb" },
  { id: 3, name: "ccc" },
]
let arr2 = [
  { id: 1, name: "aaa" },
  { id: 2, name: "bbb" },
  { id: 4, name: "ddd" },
  { id: 5, name: "eee" },
]
let arrList = arr1.concat(arr2); //两个数组对象合并
console.log('两个数组合并', arrList)
let newArrList = []; //盛放去重后数据的新数组
for (item1 of arrList) { //循环arrList数组对象的内
  let flag = true; //建立标记，判断数据是否重复，true为不重复
  for (item2 of newArrList) { //循环新数组的内容
    if (item1.id == item2.id) { //让arrList数组对象的内容与新数组的内容作比较，相同的话，改变标记为false
      flag = false;
    }
  }
  if (flag) { //判断是否重复
    newArrList.push(item1); //不重复的放入新数组。 新数组的内容会继续进行上边的循环。
  }
}
console.log('去重后的数据', newArrList)