Javascript array Filter to use external function result

Question

var data = [];

data.push({
  Id: 1,
  name: "ONE"
});
data.push({
  Id: 2,
  name: "TWO"
});
data.push({
  Id: 3,
  name: "THREE"
});

data.filter(function(item) {

  if (item.Id == 1) {
    return item.name = display();
  }
});

function display() {
  return "Formatted Text";
}

I am using javascriptarray filter function to find a value inside javascriptarray of objects. I am not able to use display() function inside this filter.

Compiler keeps telling display() function is undefined.

filter returns an array with the filtered items. you need an assignment and just return the result of the check. — Nina Scholz
– Nina Scholz, Commented Nov 23, 2017 at 18:16
You have other issues in code shown but no reason that display would be undefined — charlietfl
– charlietfl, Commented Nov 23, 2017 at 18:23

Nina Scholz · Accepted Answer · 2017-11-23 18:26:44Z

3

You could take Array#forEach, because Array#filter returns an array with the filtered items.

It looks like, you want to assign a new value with a condition, so you need no new array.

function display() {
    return "Formatted Text";
}

var data = [{ Id: 1, name: "ONE" }, { Id: 2, name: "TWO" }, { Id: 3, name: "THREE" }];

data.forEach(function(item) {
    if (item.Id === 1) {
        item.name = display();
    }
});

console.log(data);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Nov 23, 2017 at 18:26

answered Nov 23, 2017 at 18:22

Nina Scholz

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1 Comment

Matias Cicero Over a year ago

Alternatively, he can find an item by ID and then update the returned item (if any).

Danny Fardy Jhonston Bermúdez · Accepted Answer · 2017-11-23 19:23:45Z

1

I think you better need to use findIndex instead of filter like:

const arrIndex = data.findIndex(function(item) {
   return item.Id==1
});

if(arrIndex !== -1) { data[arrIndex] = display(); }

edited Nov 23, 2017 at 19:23

Danny Fardy Jhonston Bermúdez

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answered Nov 23, 2017 at 18:47

Aswin Ramesh

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Comments

Ben Aubin · Accepted Answer · 2017-11-23 19:22:28Z

0

Try this:

var data = [{
    Id: 1,
    name: "ONE"
}, {
    Id: 2,
    name: "TWO"
}, {
    Id: 3,
    name: "THREE"
}];

data.map(function(item) {

    if (item.Id == 1) {
        item.name = display();
    }
    return item;
});

function display() {
    return "Formatted Text";
}

edited Nov 23, 2017 at 19:22

Ben Aubin

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answered Nov 23, 2017 at 18:51

Chandrakant Thakkar

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2 Comments

Danny Fardy Jhonston Bermúdez Over a year ago

Add an explanation to your answer.

Chandrakant Thakkar Over a year ago

Instead of forEach just I have used map function. filter will filer the data so here map is preferable

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