Get JavaScript object from array of objects by value of property [duplicate]

Answer 1

jsObjects.find(x => x.b === 6)

From MDN:

The find() method returns a value in the array, if an element in the array satisfies the provided testing function. Otherwise undefined is returned.

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Side note: methods like find() and arrow functions are not supported by older browsers (like IE), so if you want to support these browsers, you should transpile your code using Babel.

Answer 2

If you are looking for a single result, rather than an array, may I suggest reduce?

Here is a solution in plain 'ole javascript that returns a matching object if one exists, or null if not.

var result = arr.reduce(function(prev, curr) { return (curr.b === 6) ? curr : prev; }, null);

Answer 3

Made the best/fastest part of this answer more re-usable & clear:

function getElByPropVal(myArray, prop, val){
    for (var i = 0, length = myArray.length; i < length; i++) {
        if (myArray[i][prop] == val){
            return myArray[i];
        }
    }
}

Answer 4

How about using _.find(collection, [predicate=_.identity], [fromIndex=0]) of lo-dash to get object from array of objects by object property value. You could do something like this:

var o = _.find(jsObjects, {'b': 6});

Arguments:

collection (Array|Object): The collection to inspect.
[predicate=_.identity] (Function): The function invoked per iteration.
[fromIndex=0] (number): The index to search from.

Returns

(*): Returns the matched element (in your case, {a: 5, b: 6}), else undefined.

In terms of performance, _.find() is faster as it only pulls the first object with property {'b': 6}, on the other hand, if suppose your array contains multiple objects with matching set of properties (key:value), then you should consider using _.filter() method. So in your case, as your array has a single object with this property, I would use _.find().

Answer 5

It looks like in the ECMAScript 6 proposal there are the Array methods find() and findIndex(). MDN also offers polyfills which you can include to get the functionality of these across all browsers.

find():

function isPrime(element, index, array) {
    var start = 2;
    while (start <= Math.sqrt(element)) {
        if (element % start++ < 1) return false;
    }
    return (element > 1);
}

console.log( [4, 6, 8, 12].find(isPrime) ); // undefined, not found
console.log( [4, 5, 8, 12].find(isPrime) ); // 5

findIndex():

function isPrime(element, index, array) {
    var start = 2;
    while (start <= Math.sqrt(element)) {
        if (element % start++ < 1) return false;
    }
    return (element > 1);
}

console.log( [4, 6, 8, 12].findIndex(isPrime) ); // -1, not found
console.log( [4, 6, 7, 12].findIndex(isPrime) ); // 2

Answer 6

If I understand correctly, you want to find the object in the array whose b property is 6?

var found;
jsObjects.some(function (obj) {
  if (obj.b === 6) {
    found = obj;
    return true;
  }
});

Or if you were using underscore:

var found = _.select(jsObjects, function (obj) {
  return obj.b === 6;
});