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()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/fill) — Kenigmatic, Dec 06 '17 at 20:32

Gazler · Accepted Answer · 2015-05-07T11:01:20.717

38

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 07 '15 at 11:01

answered May 07 '15 at 10:54

Gazler

83,029
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@RayonDabre yes, there is no escape – axelduch May 07 '15 at 10:59
7

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 – Nerman Apr 13 '18 at 13:59
can i use map with plain objects ?? – akshay kishore Oct 08 '18 at 14:00

sumit · Answer 2 · 2018-04-19T06:16:46.550

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 '18 at 06:16

answered Apr 19 '18 at 05:58

sumit

15,003
12
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Using `.map()` without using its return value [is an anti-pattern](https://thenewtoys.dev/blog/2021/04/17/misusing-map/). Simply use [`.forEach()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach) in this case. – Ivar Jan 17 '23 at 15:04

score 10 · Answer 3 · answered May 07 '15 at 10:58

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.

score 1 · Answer 4 · answered May 07 '15 at 10:58

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 07 '15 at 10:58

eskimomatt

195
9

javascript set all values in array of object

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