如何在对象数组上使用Array.protoype.map（）来基于其值过滤掉某些特定键？

Question

I have the following array of objects, in which some specific keys have a value which is either a string or an array. I want to get the keys with string values as it is and remove "NA" from keys with array values.

I am trying to achieve the same by doing .map method on the array, check the type of the value of each key in the data object, if an array then use .filter to remove the "NA" values.

var dataArr = [
    {
     a: 'foo',
     b: [1, 2, "NA", "NA", 3],
     c: ["NA", 6]
    },
    {
     a: 'bar',
     b: ["NA", "NA", "NA"],
     c: []
    }
];
dataArr.map(dataObj => {
    for (let key in dataObj) {
        if (key !== 'a')
            dataObj[key] = dataObj[key].filter(val => { if(val != "NA") return val})
    }
    return dataObj;
});

The above block of code works as expected but I want a better and future-proof solution. Moreover, this looks bad too.

Answer 1

You can do that using nested map() and filter()

• First of all use map() on the main array.
• Then get the entries of each object using Object.entries()
• Then use map() on the entries of each object.
• Return the value as it is if the Array.isArray is false otherwise return the filtered value of array.
• Finally use Object.fromEntries() to make an object.

 var dataArr = [ { a: 'foo', b: [1, 2, "NA", "NA", 3], c: ["NA", 6] }, { a: 'bar', b: ["NA", "NA", "NA"], c: [] } ]; const res = dataArr.map(x => Object.fromEntries( Object.entries(x) .map(([k,v]) => [k,Array.isArray(v) ? v.filter(b => b !== "NA") : v]) ) ) console.log(res) 

Answer 2

If you just want to update the original array, you could loop through the array using forEach . Then loop through each object's keys using for...in and check if it is an array using Array.isArray() . Update the property after filtering out the NA value

 const dataArr = [{a:'foo',b:[1,2,"NA","NA",3],c:["NA",6]},{a:'bar',b:["NA","NA","NA"],c:[]}]; dataArr.forEach(o => { for (const key in o) { if (Array.isArray(o[key])) o[key] = o[key].filter(s => s !== "NA") } }) console.log(dataArr) 

If you want to get a new array without mutating the original objects, you can use map like this:

 const dataArr = [{a:'foo',b:[1,2,"NA","NA",3],c:["NA",6]},{a:'bar',b:["NA","NA","NA"],c:[]}]; const newArray = dataArr.map(o => { const newObj = {}; for (const key in o) { if (Array.isArray(o[key])) newObj[key] = o[key].filter(s => s !== "NA") else newObj[key] = o[key] } return newObj; }) console.log(newArray) 

Answer 3

Use for...of on the object's entries. For each entry check if it's an array. If it's an array filter, and then assign to the new object. If not, assign without filtering. This will not mutate the original array.

 const dataArr = [{"a":"foo","b":[1,2,"NA","NA",3],"c":["NA",6]},{"a":"bar","b":["NA","NA","NA"],"c":[]}] const result = dataArr.map(dataObj => { const filterObject = {}; for (const [key, val] of Object.entries(dataObj)) { filterObject[key] = Array.isArray(val) ? dataObj[key].filter(val => val != 'NA') : val; } return filterObject; }); console.log(result); 

Answer 4

  const dataArr = [{ a: 'foo', b: [1, 2, "NA", "NA", 3], c: ["NA", 6] }, { a: 'bar', b: ["NA", "NA", "NA"], c: [] } ]; const res = dataArr.map((obj) => { for(let i in obj){ if(Array.isArray(obj[i])){ obj[i] = obj[i].filter(el=>el!=="NA") } } return obj; }); console.log('@>res', res) 

Answer 5

I guess this will be a better code refactor,pls provide with the desired output also:

dataArr.forEach(object=>{
  for (let value in object){
   let isArr = Object.prototype.toString.call(data) == '[object Array]';
   isArr? object[value] = object[value].filter(val => {return val != "NA"}):null}
 })