NodeJS find object in array by value of a key

Question

I am trying to get an object in an array by the value of one of its keys.

The array:

var arr = [
        {
            city: 'Amsterdam',
            title: 'This is Amsterdam!'
        },
        {
            city: 'Berlin',
            title: 'This is Berlin!'
        },
        {
            city: 'Budapest',
            title: 'This is Budapest!'
        }
];

I tried doing something like this with lodash but no success.

var picked = lodash.pickBy(arr, lodash.isEqual('Amsterdam');

and it returns an empty object.

Any idea on how I can do this the lodash way (if it's even possible)? I can do it the classic way, creating a new array, looping through all objects and pushing the ones matching my criteria to that new array. But is there a way to do it with lodash?

This is NOT a duplicate.

Solution 1

Using lodash and an arrow function, it should be as simple as;

var picked = lodash.filter(arr, x => x.city === 'Amsterdam');

...or alternately with object notation;

var picked = lodash.filter(arr, { 'city': 'Amsterdam' } );

Note: The above answer used to be based on pickBy, which as @torazaburo points out below was not a good choice for the use case.

Solution 2

You can use Array.prototype.find() with pure javascript:

var picked = arr.find(o => o.city === 'Amsterdam');

It is currently not compatible with all browsers, you need to check it in your environment (but it should work in NodeJS).

Solution 3

classical way is even simpler

try

var output = arr.filter(function(value){ return value.city=="Amsterdam";})

Solution 4

You can use Array.filter

As correctly pointed by @torazaburo, you do not need ternary operator return item[key]?item[key] === value:false. A simple check return item[key] === value will do fine.

var arr = [{
  city: 'Amsterdam',
  title: 'This is Amsterdam!'
}, {
  city: 'Berlin',
  title: 'This is Berlin!'
}, {
  city: 'Budapest',
  title: 'This is Budapest!'
}];

Array.prototype.findByValueOfObject = function(key, value) {
  return this.filter(function(item) {
    return (item[key] === value);
  });
}

document.write("<pre>" + JSON.stringify(arr.findByValueOfObject("city", "Amsterdam"), 0, 4) + "</pre>");

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