Javascript / Typescript - Remove from object

Question

How can I remove all objects which contain filter1 ?

const obj = {
  0: {
    'filter1': {
      'key1': {
        'email1': 'email1'
      }
    }
  },
  1: {
    'filter1': {
      'key12': {
        'email12': 'email12'
      }
    }
  },
  2: {
    'filter2': {
      'key2': {
        'email2': 'email2'
      }
    }
  }
}

Answer 1

Easy.

1. To remove an object you can use the delete API.
2. To check whether an object has a specific key you can use the hasOwnProperty API.

What you could do here is. First loop all of the keys in obj and then check whether its value (an object) has the filter1 property. If they do then delete it away.

Example:

 const obj = { 0: { 'filter1': { 'key1': { 'email1': 'email1' } } }, 1: { 'filter1': { 'key12': { 'email12': 'email12' } } }, 2: { 'filter2': { 'key2': { 'email2': 'email2' } } } }; for (var key in obj) { var objectInKey = obj[key]; if (objectInKey.hasOwnProperty("filter1")) { delete obj[key] } } console.log(JSON.stringify(obj, null, 4)); console.log(obj[0]); // <-- Should be undefined. console.log(obj[2]); // <-- Should not be undefined as obj wasn't deleted. 

Answer 2

You can use reduce to get a new object:

const newObject = Object.keys(obj).reduce((newObj, key) => {
  if (!obj[key].filter1) {
    newObj[key] = obj[key];
  }

  return newObj;
}, {});

 const obj = { 0: { 'filter1': { 'key1': { 'email1': 'email1' } } }, 1: { 'filter1': { 'key12': { 'email12': 'email12' } } }, 2: { 'filter2': { 'key2': { 'email2': 'email2' } } } }; const newObject = Object.keys(obj).reduce((newObj, key) => { if (!obj[key].filter1) { newObj[key] = obj[key]; } return newObj; }, {}); console.log(newObject); 

Or as @zerkms said, using entries :

const entries = Object.entries(obj).reduce((newObj, [key, val]) => {
  if (val.filter1) {
    return newObj;
  }

  return {
    ...newObj,
    [key]: val,
  }
}, {});

 const obj = { 0: { 'filter1': { 'key1': { 'email1': 'email1' } } }, 1: { 'filter1': { 'key12': { 'email12': 'email12' } } }, 2: { 'filter2': { 'key2': { 'email2': 'email2' } } } }; const newObject = Object.entries(obj).reduce((newObj, [key, val]) => { if (val.filter1) { return newObj; } return { ...newObj, [key]: val, } }, {}); console.log(newObject); 

Answer 3

You can use filter ,

obj = obj.filter(o => o.filter1 == undefined);

See filter reference here .

ps the obj in this example is a var not a const , see snippet below

 var obj = [ { 'filter1': { 'key1': { 'email1': 'email1' } } }, { 'filter1': { 'key12': { 'email12': 'email12' } } }, { 'filter2': { 'key2': { 'email2': 'email2' } } } ]; console.log(obj); // initial obj obj = obj.filter(o => o.filter1 == undefined); console.log(obj); // element with `filter1` property is now deleted 

Answer 4

You could use Object.entries to get an array of key-value pairs, then use Array#reduce to filter the data and translate it back into an object format.

 const obj = { 0: { 'filter1': { 'key1': { 'email1': 'email1' } } }, 1: { 'filter1': { 'key12': { 'email12': 'email12' } } }, 2: { 'filter2': { 'key2': { 'email2': 'email2' } } } }; console.log(Object.entries(obj).reduce((m, [k, v]) => (v.filter1 || (m[k] = v), m), {})); // { "2": { "filter2": { "key2": { "email2": "email2" } } } } 

Further reading:

• Object.entries ^(mdn)
• Array#reduce ^(mdn)

Answer 5

To modify the object in place (rather than copying it, or creating arrays), I'd just use a simple loop and a delete:

let k = Object.keys(obj);
for (let i = 0; i < k.length ; i++ ) {
    if (obj[k[i]].hasOwnProperty('filter1')) delete obj[k[i]];
}