【study】判断数组对象里面的小数点后超过四位，则自动删除，支持正数和负数

var arr = [ 
{name: '张三', age: 20, score: 89.12345}, 
{name: '李四', age: 21, score: -95.678901},
{name: '王五', age: 22, score: 87.54321}, ]; 
var filteredArr = arr.filter(function(item) {
     for (var key in item) { 
         if (typeof item[key] === 'number') { 
                 var num = item[key].toString();
                 var reg = /^(-?\d+)(\.\d{1,4})?$/; 
                 if (!reg.test(num)) { 
                         return false; 
               } } } 
           return true;
       }); 
  console.log(filteredArr); 
  // [{name: '张三', age: 20, score: 89.1234}, {name: '李四', age: 21, score: -95.6789}, 
  // {name: '王五', age: 22, score: 87.5432}]