JavaScript: find objects in array with property containing a specific string

Question

In JavaScript, if you have an array of objects with a format like:

Persons = {
  'First Name': 'Dark',
  'Last Name': 'Defender',
  Age: 26
}

And you need to go through each to find the persons with a certain string in their last name, for example: ‘der’.

How would you use the .find() to find and return the persons with ‘der’ in their last name?

I have tried:

personArray = persons.find(({[“Last Name”]}) => “Last Name” === ‘der’);

It works for age but I can’t seem to get the syntax right for multiple word key like “Last Name”.

kind user · Accepted Answer · 2020-10-21 22:44:29Z

1

You could use Array#filter to filter out all of these entries where Last Name includes "der".

const arr = [
   { "First Name": 'Dark', "Last Name": 'Defender', Age: 26},
   { "First Name": 'Dark', "Last Name": 'Abc', Age: 26},
   { "First Name": 'Dark', "Last Name": 'Xyz', Age: 26},
];

const res = arr.filter(({ ["Last Name"]: name }) => name && name.includes('der'));

console.log(res);

edited Oct 21, 2020 at 22:44

answered Oct 21, 2020 at 19:38

kind user

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2 Comments

DarkDefender Over a year ago

Thank you for the response. I tried this method too and it also gives me a “TypeError: Cannot read property ‘includes’ of null”

kind user Over a year ago

@DarkDefender Updated answer.

Julia · Accepted Answer · 2020-10-21 19:42:47Z

0

You can use filter and includes methods

  const persons = [
    { "First Name": "Dark", "Last Name": "Defender", Age: 26 },
    { "First Name": "Carlos", "Last Name": "Defback" },
    { "First Name": "Carlos", "Last Name": "None"}
  ];
  const foundPersons = persons.filter(person =>
    person["Last Name"].includes("Def")
  );
  console.log('foundPersons: ', foundPersons)

answered Oct 21, 2020 at 19:42

Julia

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Comments

fxnoob · Accepted Answer · 2020-10-21 19:45:35Z

0

As you said we have an array of the object(persons) like this:-

const arr = [
 { “First Name”: “Dark”, “Last Name”: “Defender”, Age: 26},
 { “First Name”: “Dark”, “Last Name”: “Defender”, Age: 26},
 .
 .
 . etc
]

// do this
const matchingObj = arr.find(el => el["Last Name"].endsWith("der")); // returns first occurence
console.log(matchingObj)

answered Oct 21, 2020 at 19:45

fxnoob

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Comments

Majed Badawi · Accepted Answer · 2020-10-22 06:52:36Z

0

You can use .filter and .indexOf to check for the substring in each person's last name:

const persons = [
  { 'First Name': 'Dark', 'Last Name': 'Defender', Age: 26},
  { 'First Name': 'Ben', 'Last Name': 'Robbins', Age: 22},
  { 'First Name': 'John', 'Last Name': 'Beans', Age: 23}
];

const personArray = persons.filter(person => 
  person['Last Name'] && person['Last Name'].indexOf('der') !== -1
);

console.log(personArray);

edited Oct 22, 2020 at 6:52

answered Oct 21, 2020 at 19:38

Majed Badawi

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2 Comments

DarkDefender Over a year ago

Thank you for the response. Using this method gives me a “TypeError: Cannot read property ‘indexOf’ of null”

Majed Badawi Over a year ago

Make sure every object has a 'Last Name' property as above. Yoi can also check if person['Last Name'] exists before the comparison

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