如果对象与新数组不匹配，则从前一个数组中删除对象

Question

I am trying to remove the values that don't match in the previous array to the values in the new array.

var previous = [
    {m: "195/50 15"},
    {m: "195/50 16"},
    {m: "195/55 15"},
    {m: "195/55 16"},
    {m: "195/55 20"}
];
var newOne = [
    {m: "195/55 15"},
    {m: "195/55 16"},
    {m: "195/55 20"}
];

console.log( previous.filter((obj) => obj['m'] !== newOne['m']) );

And if the new array is empty, then the filter should return an empty array.

The method I am trying above doesn't work.

Answer 1

Try using some to determine if the value is in the other array:

 var previous = [ {m: "195/50 15"}, {m: "195/50 16"}, {m: "195/55 15"}, {m: "195/55 16"}, {m: "195/55 20"} ]; var newOne = [ {m: "195/55 15"}, {m: "195/55 16"}, {m: "195/55 20"} ]; const result = previous.filter(p => { return newOne.some(n => nm === pm); }) console.log(result);

Answer 2

Comparison should be like this

var previous = [
    {m: "195/50 15"},
    {m: "195/50 16"},
    {m: "195/55 15"},
    {m: "195/55 16"},
    {m: "195/55 20"}
];
var newOne = [
    {m: "195/55 15"},
    {m: "195/55 16"},
    {m: "195/55 20"}
];

console.log( previous.filter((obj, i) => newOne[i] && obj['m'] !== newOne[i]['m']) );

Answer 3

In your code you are using filter function that runs through objects inside previous array and compares each object value with newOne['m'] which returns undefined

    let newArray = []

    previous.forEach(pobj => {
      newOne.forEach(nobj => {
        if(pobj['m'] === nobj['m']){
          newArray.push(pobj)
        }
      })
    })

    console.log(newArray)