How to update all matches in array of objects?

Question

I want to update this array of objects

var a = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"}]

to

var a = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"found it"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"found it"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"found it"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"found it"}]

This only updates the first match in this array, but I need it to update all matches.

a.find(x => x.uuid == "93161c2b-6c56-4204-b6b5-c5c3cee0f38a").answer = "found it"

I know I can loop through the array to change each answer matching the uuid, but is there a better way to do this?

You need to loop through the array to change each answer matching the uuid. — pilchard
– pilchard, Commented Dec 26, 2021 at 12:36
If the id values are in essentially random order, all you can do is sequentially search through the array with a loop or .forEach(). You could sort the array and then do a binary search, or (probably better) transform the array into a map from uuid value to a container object (or array of objects) with "answer" values or whatever else you want. — Pointy
– Pointy, Commented Dec 26, 2021 at 12:37

Jack Bashford · Accepted Answer · 2021-12-26 12:38:21Z

3

A short and simple way to loop through them all and change them would be with forEach:

var a = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"}];

a.forEach((elem, idx) => {
  if (elem.uuid == "93161c2b-6c56-4204-b6b5-c5c3cee0f38a") { 
    elem.answer = "found it";
  }
});

console.log(a);

Alternatively, you can use map, another shorthand way to do effectively what you described. It returns a new array:

var a = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"}];

a = a.map(elem => elem.uuid == "93161c2b-6c56-4204-b6b5-c5c3cee0f38a" ? ({ ...elem, answer: "found it" }) : elem);

console.log(a);

Note that this still will loop through the array, but it's a neater way to do it (creating a new array based off of your original one). I used object spreading { ...elem } syntax above so that it'll preserve other properties in your objects too if there are more. Another, more verbose way to do this would be:

var a = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"}];

a = a.map(elem => {
  if (elem.uuid == "93161c2b-6c56-4204-b6b5-c5c3cee0f38a") { 
    elem.answer = "found it";
  }
  return elem;
});

console.log(a);

edited Dec 26, 2021 at 12:38

answered Dec 26, 2021 at 12:36

Jack Bashford

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2 Comments

Pointy Over a year ago

Or .forEach(), which would not incur the (very minor) overhead of making a new array

Jack Bashford Over a year ago

Yes @Pointy, just about to mention that one - realised it'd probably be more effective here since only some items require mutation. Thanks!

Sanket Shah · Accepted Answer · 2021-12-26 12:47:51Z

There are 2 ways to achieve the result:

1) Using forEach: (Preferred way)

var data = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"}]

const updateRecord = (data, id) => {
  data.forEach((record) => {
    if(record.uuid === id){
      record.answer = 'found it'
    }
    return record
  })
  
  return data
}

console.log(updateRecord(data, "93161c2b-6c56-4204-b6b5-c5c3cee0f38a"))

2) Using map:

var data = [{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"},
{"uuid":"e468c4ff-98c8-4d53-986e-529e4a199540","answer":"none"},
{"uuid":"f71835b7-b57a-4971-9f0b-ff0474fd495e","answer":"none"},
{"uuid":"93161c2b-6c56-4204-b6b5-c5c3cee0f38a","answer":"none"}]


const updatedData = data.map(record => record.uuid == "93161c2b-6c56-4204-b6b5-c5c3cee0f38a" ? ({ ...record, answer: "found it" }) : record);

console.log(updatedData);

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