javascript set all values in array of object

Question

Two part question about similar problems. I've got 2 different arrays,

array 1:

 array1 = [{
     name : "users",
     checked : true
   }, {
     name : "active users",
     checked : false
   }, {
     name : "completions",
     checked : false
   }]

I would like to know if there is an easy way to set all the checked values to true at once. I know this is possible with a for loop:

  for (var i = 0 ; i < array.length ; i++) {
    array[i].checked = false
  }

Even though this is not a lot of code i'm just curious if there is a way to do this without iterating over every object in the array. (not sure if this is even possible or whether this makes any difference whatsoever, so if please correct me if i am wrong about any of this).

array 2:

array2 = [{
     value1 : false,
     value2 : true,
     value3 : false,
     value4 : false, 
     value5 : false,   
   }]

Is it possible to simply set all the values to true or false at once (again i can use a for loop, but would prefer not to)

(i'm using angular and lodash, but haven't been able to find a 'lodash' or 'angular' solution, but any solution will do)

array2 only has 1 element: an object with five properties. If it were an array of values or an array of properties, and if using ES6 is okay, then you could use Array.prototype.fill() — Kenigmatic
– Kenigmatic, Commented Dec 6, 2017 at 20:32

Gazler · Accepted Answer · 2015-05-07 11:01:20Z

40

You can't do this without looping over the elements, however there are functional abstractions you can use instead of for:

For array 1, you can use map

array1.map(function(x) { 
  x.checked = true; 
  return x
});

Or using _.map from lodash:

_.map(array1, function(x) { 
  x.checked = true; 
  return x
});

For array 2 you can use _.mapValues from lodash.

_.mapValues(array2[0], function() {
  return true;
});

You can see that lodash implements _.map using while at https://github.com/lodash/lodash/blob/a1b15df6489f47498edda244552c9804e046a45d/lodash.js#L3125

edited May 7, 2015 at 11:01

answered May 7, 2015 at 10:54

Gazler

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3 Comments

a-d Over a year ago

@RayonDabre yes, there is no escape

Nerman Over a year ago

I believe .forEach is more suitable in this scenario. Unless there is a case for creating a new array of objects, which .map effectively does. I know it's an old thread, but someone might find my contribution useful

akshay kishore Over a year ago

can i use map with plain objects ??

sumit · Accepted Answer · 2018-04-19 06:16:46Z

25

You can use es6 fat arrow and make one liner but still it involves iteration .

array1.map(a=>a.checked=true);

array1 = [{
     name : "users",
     checked : true
   }, {
     name : "active users",
     checked : false
   }, {
     name : "completions",
     checked : false
   }]
   array1.map(a=>a.checked=true);
   console.log(array1);

edited Apr 19, 2018 at 6:16

answered Apr 19, 2018 at 5:58

sumit

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1 Comment

Ivar Over a year ago

Using .map() without using its return value is an anti-pattern. Simply use .forEach() in this case.

Fourat · Accepted Answer · 2015-05-07 10:58:26Z

10

Even though this is not a lot of code i'm just curious if there is a way to do this without iterating over every object in the array. (not sure if this is even possible or whether this makes any difference whatsoever, so if please correct me if i am wrong about any of this).

Is it possible to simply set all the values to true or false at once (again i can use a for loop, but would prefer not to)

No ! You can't visit all towns without visiting each of them. There are shortcuts with jQuery like $.each and lodash like _.map but it's just a function that's doing what you would do with the for loop.

answered May 7, 2015 at 10:58

Fourat

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Comments

eskimomatt · Accepted Answer · 2015-05-07 10:58:10Z

1

There is no way to set the value of each object in an array without iterating (looping) through the array as you mentioned in your question.

answered May 7, 2015 at 10:58

eskimomatt

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