Filter an array of objects with .filter

Question

If have a JSON object, how can I use.filter to filter my array based on a filters object.

data = [
   {month: 'Sep', name: 'Fred', department: 'Accounting'},
   {month: 'Sep', name: 'David', department: 'Sales'},
   {month: 'Oct', name: 'Jon', department: 'Sales'}
]

filters = {
    month: [],
    name: ['Jon'],
    department: ['Sales','Accounting']
}

Theres no 2d array here. Its unclear what you want to do

Jonas Wilms
– Jonas Wilms

2017-12-12 18:40:59 +00:00
Commented Dec 12, 2017 at 18:40 — Jonas Wilms
– Jonas Wilms, Commented Dec 12, 2017 at 18:40
Excellent observation

user1093111
– user1093111

2017-12-12 18:42:59 +00:00
Commented Dec 12, 2017 at 18:42 — user1093111
– user1093111, Commented Dec 12, 2017 at 18:42
I changed the title

user1093111
– user1093111

2017-12-12 19:02:24 +00:00
Commented Dec 12, 2017 at 19:02 — user1093111
– user1093111, Commented Dec 12, 2017 at 19:02

Patrick Roberts · Accepted Answer · 2017-12-12 18:55:40Z

1

let data = [
 { month: 'Sep', name: 'Fred', department: 'Accounting' },
 { month: 'Sep', name: 'David', department: 'Sales' },
 { month: 'Oct', name: 'Jon', department: 'Sales' }
];

let filters = {
  month: [],
  name: ['Jon'],
  department: ['Sales', 'Accounting']
};

let matches = data.filter(function (o) {
  // iterate through keys of filter object
  for (const key in this) {
    // if filter array is empty and
    // value is not in filter array
    if (this[key].length > 0 && !this[key].includes(o[key])) {
      // object is not match
      return false;
    }
  }
  
  // if object passed every filter array
  // object is match
  return true;
}, filters);

console.log(matches);

A more compact way of writing it could be like this:

let data = [
  { month: 'Sep', name: 'Fred', department: 'Accounting' },
  { month: 'Sep', name: 'David', department: 'Sales' },
  { month: 'Oct', name: 'Jon', department: 'Sales' }
];

let filters = {
  month: [],
  name: ['Jon'],
  department: ['Sales', 'Accounting']
};

let matches = data.filter(function (o) {
  return Object.keys(this).every(
    key => this[key].length === 0 || this[key].includes(o[key])
  );
}, filters);

console.log(matches);

edited Dec 12, 2017 at 18:55

answered Dec 12, 2017 at 18:47

Patrick Roberts

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2 Comments

Jonas Wilms Over a year ago

I dont see any advantage of key of Object.keys(this) over key in filters

Patrick Roberts Over a year ago

@JonasW. one advantage is that the former does not iterate inherited enumerable keys, only own enumerable, but I do agree in this case it's easier to use for...in.

Jonas Wilms · Accepted Answer · 2017-12-12 18:43:34Z

1

 const result = data.filter(entry => {
   for(var key in filters){
     if(filters[key].length && !filters[key].includes(entry[key]) )
        return false;
   }
   return true;
});

You could filter your data by checking every filter's key to exist in the object and that its value is included in the filtering array.

answered Dec 12, 2017 at 18:43

Jonas Wilms

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Comments

Nenad Vracar · Accepted Answer · 2017-12-12 18:44:56Z

1

You can do this with filter() and every() methods.

var data = [
   {month: 'Sep', name: 'Fred', department: 'Accounting'},
   {month: 'Sep', name: 'David', department: 'Sales'},
   {month: 'Oct', name: 'Jon', department: 'Sales'}
]

var filters = {
    month: [],
    name: ['Jon'],
    department: ['Sales','Accounting']
}

var result = data.filter(e => {
  return Object.keys(filters).every(f => {
    return filters[f].includes(e[f]) || !filters[f].length
  })
})


console.log(result)

answered Dec 12, 2017 at 18:44

Nenad Vracar

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Comments

rob_ · Accepted Answer · 2017-12-12 18:39:50Z

0

data.filter(obj => filters.month.indexOf(obj.month) > -1 && filters.name.indexOf(obj.name) > -1 && filters.department.indexOf(obj.department) > -1)

answered Dec 12, 2017 at 18:39

rob_

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1 Comment

Sterling Archer Over a year ago

Please explain your code. Without teaching, you're just dumping out an answer, which is a bad answer.

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