rem如何实现自适应

var baseSize = 50, // 基数
    baseWidth = 375, //量取值大小
    fontSize =  (document.documentElement.clientWidth / baseWidth * baseSize).toFixed(2) ; //这个就是动态font-size值

/** 方法一：
 * 1.构建一个新的数组存放结果
 * 2.for循环中每次从原数组中取出一个元素，用这个元素循环与结果数组对比
 * 3.若结果数组中没有该元素，则存到结果数组中
 * 缺陷：不能去重数组中得引用类型的值和NaN
*/
function unique(array){
  var result = [];
  for(var i = 0;i < array.length; i++){
    if(result.indexOf(array[i]) == -1) {
      result.push(array[i]);
    }
  }
  return result;
}

// [1,2,1,2,‘1‘,‘2‘,0,‘1‘,‘你好‘,‘1‘,‘你好‘,NaN,NaN] => [1, 2, "1", "2", 0, "你好",NaN,NaN]
// [{id: ‘1‘}, {id: ‘1‘}] => [{id: ‘1‘}, {id: ‘1‘}]

var path = ‘www.u.com/home?id=2&type=0&dtype=-1‘;

function parseUrl(url) {
  var result = [];
  var tmp = (url.split(‘?‘))[1];
  var tmpArr = tmp.split(‘&‘);
  tmpArr.map(function(v, k) {
    var value, key;
    var obj = {};
    key = (v.split(‘=‘))[0];
    value = (v.split(‘=‘))[1];
    obj[key] = value;
    result.push(obj)
  })
  
  return result;
}

console.log(parseUrl(path)); //[{id: ‘2‘},{type: ‘0‘},{dtype: ‘-1‘}]



//功能：获取url中的参数的值
function UrlSearch(url) {
  var name,value;
  var str = url; //取得整个地址栏
  var num = str.indexOf("?");
  str = str.substr(num+1); //取得所有参数   stringvar.substr(start [, length ]

  var arr=str.split("&"); //各个参数放到数组里
  for(var i=0;i < arr.length;i++){
    num = arr[i].indexOf("=");
    if(num>0){
      name=arr[i].substring(0,num);
      value=arr[i].substr(num+1);
      this[name]=value;
    }
  }
}

// 测试
var path = ‘www.u.com/home?id=2&type=0&dtype=-1‘;
var Request= new UrlSearch(path); //实例化
console.log(Request); //[{dtype: ‘-1‘},{id: ‘2‘},{type: ‘0‘}]
var nickname = encodeURIComponent(Request.dtype);
console.log(nickname); //-1



//功能：修改url参数值
function changeURLArg(url,arg,arg_val){
  var pattern=arg+‘=([^&]*)‘;
  var replaceText=arg+‘=‘+arg_val;
  if(url.match(pattern)){
    var tmp=‘/(‘+ arg+‘=)([^&]*)/gi‘;
    tmp=url.replace(eval(tmp),replaceText);
    return tmp;
  }else{
    if(url.match(‘[\?]‘)){
      return url+‘&‘+replaceText;
    }else{
      return url+‘?‘+replaceText;
    }
  }
  return url+‘\n‘+arg+‘\n‘+arg_val;
}

var path = ‘www.u.com/home?id=2&type=0&dtype=-1‘;
console.log(changeURLArg(path,‘type‘,4)); //"www.u.com/home?id=2&type=4&dtype=4"