I am trying to edit an array of objects that I have based on another array.

For example, this is my array of objects:

var objs = [{ 
   attending: 0, user: '123' 
}, { 
   attending: 0, user: '456' 
}, { 
   attending: 0, user: '789' 
}];

And this is my array:

var arr = ['945', '456']

Since 456 exists within arr, I would like to remove that object from obj. Hence being the final result of:

var objs = [{ 
   attending: 0, user: '123' 
}, { 
   attending: 0, user: '789' 
}];

I have tried both omit and pullByAll yet had no luck:

var newObj = _.omit(obj, arr);
var newObj = _.pullAllBy(obj, arr, 'user');

What would be the best approach to this while using Lodash? I understand that creating a Javascript function for this would be quite simple, although my app requires this to be done quite often, so would be good to have a simple Lodash function that is accessible.

I am trying to edit an array of objects that I have based on another array.

For example, this is my array of objects:

var objs = [{ 
   attending: 0, user: '123' 
}, { 
   attending: 0, user: '456' 
}, { 
   attending: 0, user: '789' 
}];

And this is my array:

var arr = ['945', '456']

Since 456 exists within arr, I would like to remove that object from obj. Hence being the final result of:

var objs = [{ 
   attending: 0, user: '123' 
}, { 
   attending: 0, user: '789' 
}];

I have tried both omit and pullByAll yet had no luck:

var newObj = _.omit(obj, arr);
var newObj = _.pullAllBy(obj, arr, 'user');

What would be the best approach to this while using Lodash? I understand that creating a Javascript function for this would be quite simple, although my app requires this to be done quite often, so would be good to have a simple Lodash function that is accessible.

• javascript
• underscore.js
• lodash

• Why do you feel the need for using lodash? If performance is your concern, using vanilla js probably more transparent and easier to optimize. – lipp Commented May 30, 2016 at 7:08
• How many elements (magnitude) are you expecting in arr and objs respectively? Do you "re-query" objs for every request or is it "global"? – lipp Commented May 30, 2016 at 7:17

4 Answers 4

You can use native js method to do that.

var newObj = objs.filter(function(obj) {
  return arr.indexOf(obj.user) != -1
});

if you are using ES6 its even more simple

var newObj = objs.filter(obj => arr.indexOf(obj.user) != -1);

There is this video which explains this concept very nicely.

As asked, here it is in lodash:

var newObj = _.filter(objs, function(obj) {
  return _.indexOf(arr, obj.user) !== -1;
});

We can debate plain js vs lodash till the cows e home, but 1) the question asks for lodash, and 2) if objs or arr are null, the plain js answers will throw an error.

With plain JS this would work:

var newObj = objs.filter(function(obj) {
   return arr.indexOf(obj.user) !== -1
})

I was able to solve this with a bination of both forEach() and remove()

_(obj).forEach(function(value) {
    _.remove(arr, {
        user: value
    });
});