Can't get single value after iteration on array of objects

Question

I use this code to iterate on the JavaScript objects array and return value:

this.selectedClient = _.forEach(self.clients, function (client) {
    if (client.IdentityNumber == -1) {
        return client;
    }
}) 

this.clients=[{firstName:"Tywin", lastName:"Lannister", age:46, IdentityNumber:2},
              {firstName:"Arya", lastName:"Starck", age:46, IdentityNumber:-1},
              {firstName:"John", lastName:"Snow", age:46, IdentityNumber:12},
              {firstName:"Robb", lastName:"Starck", age:46, IdentityNumber:24}];

But after iteration is done I expect that selectedClient veriable will get single item:

{firstName:"Arya", lastName:"Starck", age:46, IdentityNumber:-1}

But instead selectedClient veriable get all items in clients variable.

Any idea why I can't get single value after iteration on clients variable?

Tushar · Accepted Answer · 2016-06-09 12:59:26Z

4

You cannot return data from forEach.

Copying from the Lodash Docs for forEach

Iteratee functions may exit iteration early by explicitly returning false.

Use _.find().

var selectedClient = _.find(clients, function (client) {
    if (client.IdentityNumber == -1) {
        return client;
    }
});

You can also use shorter syntax with Object as second parameter.

_.find(clients, {IdentityNumber: -1});

var clients = [{
    firstName: "Tywin",
    lastName: "Lannister",
    age: 46,
    IdentityNumber: 2
}, {
    firstName: "Arya",
    lastName: "Starck",
    age: 46,
    IdentityNumber: -1
}, {
    firstName: "John",
    lastName: "Snow",
    age: 46,
    IdentityNumber: 12
}, {
    firstName: "Robb",
    lastName: "Starck",
    age: 46,
    IdentityNumber: 24
}];


var selectedClient = _.find(clients, {IdentityNumber: -1});

console.log(selectedClient);

<script src="https://cdn.jsdelivr.net/lodash/4.13.1/lodash.min.js"></script>

For Vanilla Lovers, use Array#find

clients.find(c => c.IdentityNumber === -1)

var clients = [{
    firstName: "Tywin",
    lastName: "Lannister",
    age: 46,
    IdentityNumber: 2
}, {
    firstName: "Arya",
    lastName: "Starck",
    age: 46,
    IdentityNumber: -1
}, {
    firstName: "Robb",
    lastName: "Starck",
    age: 46,
    IdentityNumber: 24
}];

var selectedClient = clients.find(c => c.IdentityNumber === -1);
console.log(selectedClient);

edited Jun 9, 2016 at 12:59

answered Jun 9, 2016 at 12:53

Tushar

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5 Comments

Michael Over a year ago

what if I want to return a single property from client object for example Id?

Tushar Over a year ago

@Michael _.find(clients, {IdentityNumber: -1}) || {}.id

Michael Over a year ago

could you please give brief explanation of code above?

Michael Over a year ago

this row _.find(clients, {IdentityNumber: -1}) || {}.id returns all object but not property

Michael Over a year ago

after some research I modify your vanilla code and I got desired result: _.result(_.find(self.clients, { IdentityNumber: -1 }), 'Id');

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