how to filter an element of array inside array of objects in java-script without using for loop?

Question

my data. data also has empty entries

const aadharData = [
  {
    firstName: "Ritam",
    lastName: "Singhal",
    address: {
      location: "rampur",
      state: "up",
    },
    hasDrivingLicense: false,
    emails: ["[email protected]", "[email protected]", "[email protected]"],
  },
  {
    firstName: "Siddarth",
    lastName: "Singhal",
    address: {
      location: "chandigarh",
      state: "haryana",
    },
    hasDrivingLicense: false,
    emails: ["[email protected]"],
  },
];

1. what I managed to filter out was a list of emails and fullname. with following code

let gmailList = [];
aadharData.forEach((info) => {
  if (info.emails) {
    let fullname = info.firstName + " " + info.lastName;
    let email = info.emails;
    gmailList.push({ fullname, email });
  }
});

2. I want to filter only those emailID that are gmails. however, I don't know how to iterate inside the property. I tried using forEach, some, and filter inside forEach but that doesn't seem to work or at least I don't know how to use them effectively. my assignment states I can't use for loop. finally, i want results in the format as

 { fullname, gmail }

example

{ fullname: "Mayank Attri", email: ["[email protected]"] };

DecPK · Accepted Answer · 2021-09-04 08:00:54Z

1

You can easily achieve the result using map and filter. You can filter the email as

o.emails && o.emails.filter((e) => e.match(/gmail.com$/))

const aadharData = [{
    firstName: "Ritam",
    lastName: "Singhal",
    address: {
      location: "rampur",
      state: "up",
    },
    hasDrivingLicense: false,
    emails: ["[email protected]", "[email protected]", "[email protected]"],
  },
  {
    firstName: "Siddarth",
    lastName: "Singhal",
    address: {
      location: "chandigarh",
      state: "haryana",
    },
    hasDrivingLicense: false,
    emails: ["[email protected]"],
  },
  {
    firstName: "Mukul",
    lastName: "Gaddiyan",
    address: {
      location: "lucknow",
      state: "up",
    },
    hasDrivingLicense: false,
  },
  {
    firstName: "Mayank",
    lastName: "Attri",
    address: {
      location: "alwar",
      state: "rajasthan",
    },
    hasDrivingLicense: true,
    emails: ["[email protected]"],
  },
  {
    firstName: "Akash",
    lastName: "Agarwal",
    address: {
      location: "gurgaon",
      state: "haryana",
    },
    hasDrivingLicense: true,
    emails: ["[email protected]", "[email protected]", "[email protected]"],
  },
];

const result = aadharData.map((o) => ({
  fullname: `${o.firstName} ${o.lastName}`,
  emails: o.emails && o.emails.filter((e) => e.match(/gmail.com$/)),
}));

console.log(result);

/* This is not a part of answer. It is just to give the output fill height. So IGNORE IT */

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

Updated: If you want result your resultant array contains only emails if there are more than one emails

const aadharData = [{
    firstName: "Ritam",
    lastName: "Singhal",
    address: {
      location: "rampur",
      state: "up",
    },
    hasDrivingLicense: false,
    emails: ["[email protected]", "[email protected]", "[email protected]"],
  },
  {
    firstName: "Siddarth",
    lastName: "Singhal",
    address: {
      location: "chandigarh",
      state: "haryana",
    },
    hasDrivingLicense: false,
    emails: ["[email protected]"],
  },
  {
    firstName: "Mukul",
    lastName: "Gaddiyan",
    address: {
      location: "lucknow",
      state: "up",
    },
    hasDrivingLicense: false,
  },
  {
    firstName: "Mayank",
    lastName: "Attri",
    address: {
      location: "alwar",
      state: "rajasthan",
    },
    hasDrivingLicense: true,
    emails: ["[email protected]"],
  },
  {
    firstName: "Akash",
    lastName: "Agarwal",
    address: {
      location: "gurgaon",
      state: "haryana",
    },
    hasDrivingLicense: true,
    emails: ["[email protected]", "[email protected]", "[email protected]"],
  },
];

const result = aadharData.reduce((acc, curr) => {
  if (curr.emails) {
    const emails = curr.emails.filter((e) => e.match(/gmail.com$/));
    emails.length &&
      acc.push({
        fullname: `${curr.firstName} ${curr.lastName}`,
        emails,
      });
  }
  return acc;
}, []);

console.log(result);

/* This is not a part of answer. It is just to give the output fill height. So IGNORE IT */

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

edited Sep 4, 2021 at 8:00

answered Sep 4, 2021 at 4:59

DecPK

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9 Comments

Jay Sardar Over a year ago

thank you for the answer. can you please tell me what you used ? the $ symbol i dont know what it is. if you can refer me some link it would be great help. also code runs here but on vs code it shows error

TypeError: Cannot read property 'filter' of undefined     at c:\Users\JAY SARDAR\project\es6\functionUp\firstproject\src\Routes\index.js:82:22

Jay Sardar Over a year ago

i got the similar error when i tried to use info.emails.some(condition) also i tried info.emails.filter, but i got same error TypeError: Cannot read property 'filter' of undefined

Jay Sardar Over a year ago

also its not specific to vs code. i got same error on codepen codepen.io/blue-berd/pen/PojqzdL

DecPK Over a year ago

@JaySardar I've updated the answer, $ is used as Template string

DecPK Over a year ago

Error was because some objects in array doesn't have the emails property.

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