How to use multiple criteria with JavaScript .filter()?

Question

I'm trying to filter an array using the method from this post, but I can't seem to get it working. My setup is below, which I'm expecting to result in an empty array because the one object in the array matches the filter criteria, but it is resulting in the original array being returned in the console. Is there something here that I'm missing?

var myArr = [
    {
        link_source_id: "act_0",
        link_source_name: "Hello World!",
        link_target_id: "obj_1",
        link_target_name: "Document",
        link_type: "activity-object-input"
    }
]

var myFilter = {
    link_source_id: "act_0",
    link_target_id: "obj_1"
}

myArr = myArr.filter(function (item) {
  for (var key in myFilter) {
    if (
      item[key] === undefined ||
      item[key] !== myFilter[key]
    )
      return false;
  }
  return true;
});

console.log(myArr)

try => `if () else return true` - btw it will return the `array` — Always Helping, Sep 20 '20 at 00:56
....your condition will be `true` if either of the key values are matchings - if `both` did match it will return `false` else always `true` — Always Helping, Sep 20 '20 at 01:03
If you swap return false / true, then an empty array is returned because the conditions both return false for the object in your array — Dream_Cap, Sep 20 '20 at 01:06
@Dream_Cap I just did that and everything is working now. Feel silly that I didn't catch that. — userNick, Sep 20 '20 at 01:11

score 0 · Answer 1 · answered Sep 20 '20 at 01:09

0

here is an example

const obj = [
    {id:1 , name:"Alice"} , {id:1,name:"Bob"}
]

const arr = obj.filter((oneObj)=>{
    return (oneObj.id==1 && oneObj.name=="Alice")
})

console.log(arr); // will log [{id:1 , name:"Alice"}]

answered Sep 20 '20 at 01:09

Ahmed Magdy

1,054
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16

score 0 · Accepted Answer · answered Sep 20 '20 at 01:13

I'll leave this up for others, but answer my own questions based on the comments in the OP. Swapping the true and false statements should resolve the issue:

var myArr = [
    {
        link_source_id: "act_0",
        link_source_name: "Hello World!",
        link_target_id: "obj_1",
        link_target_name: "Document",
        link_type: "activity-object-input"
    }
]

var myFilter = {
    link_source_id: "act_0",
    link_target_id: "obj_1"
}

myArr = myArr.filter(function (item) {
  for (var key in myFilter) {
    if (
      item[key] === undefined ||
      item[key] !== myFilter[key]
    )
      return true;
  }
  return false;
});

console.log(myArr)

both the `code-snippets` - in your question and answer are correct. One filter is `positive` (it filters out matches) and the other is `negative` (it filters out un-matched items). — Aakash, Sep 20 '20 at 01:56

How to use multiple criteria with JavaScript .filter()?

2 Answers2