Get JavaScript object from array of objects by value of property
Get JavaScript object from array of objects by value of property
Question
Let's say I have an array of four objects:
var jsObjects = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
];
Is there a way that I can get the third object ({a: 5, b: 6}
) by the value of the property b
for example without a for...in
loop?
Popular Answer
Filter
array of objects, which property matches value, returns array:
var result = jsObjects.filter(obj => {
return obj.b === 6
})
See the MDN Docs on Array.prototype.filter()
const jsObjects = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
]
let result = jsObjects.filter(obj => {
return obj.b === 6
})
console.log(result)
Find
the value of the first element/object in the array, otherwise undefined
is returned.
var result = jsObjects.find(obj => {
return obj.b === 6
})
See the MDN Docs on Array.prototype.find()
const jsObjects = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
]
let result = jsObjects.find(obj => {
return obj.b === 6
})
console.log(result)
Read more… Read less…
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. Otherwiseundefined
is returned.
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.
I don't know why you are against a for loop (presumably you meant a for loop, not specifically for..in), they are fast and easy to read. Anyhow, here's some options.
For loop:
function getByValue(arr, value) {
for (var i=0, iLen=arr.length; i<iLen; i++) {
if (arr[i].b == value) return arr[i];
}
}
.filter
function getByValue2(arr, value) {
var result = arr.filter(function(o){return o.b == value;} );
return result? result[0] : null; // or undefined
}
.forEach
function getByValue3(arr, value) {
var result = [];
arr.forEach(function(o){if (o.b == value) result.push(o);} );
return result? result[0] : null; // or undefined
}
If, on the other hand you really did mean for..in and want to find an object with any property with a value of 6, then you must use for..in unless you pass the names to check. e.g.
function getByValue4(arr, value) {
var o;
for (var i=0, iLen=arr.length; i<iLen; i++) {
o = arr[i];
for (var p in o) {
if (o.hasOwnProperty(p) && o[p] == value) {
return o;
}
}
}
}
Try Array filter method for filter the array of objects
with property
.
var jsObjects = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
];
using array filter method:
var filterObj = jsObjects.filter(function(e) {
return e.b == 6;
});
using for in loop :
for (var i in jsObjects) {
if (jsObjects[i].b == 6) {
console.log(jsObjects[i]); // {a: 5, b: 6}
}
}
Working fiddle : https://jsfiddle.net/uq9n9g77/
OK, there are few ways to do that, but let's start with the simplest one and latest approach to do this, this function is called find()
.
Just be careful when you using find
to as even IE11 dosn't support it, so it needs to be transpiled...
so you have this object as you said:
var jsObjects = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
];
and you can write a function and get it like this:
function filterValue(obj, key, value) {
return obj.find(function(v){ return v[key] === value});
}
and use the function like this:
filterValue(jsObjects, "b", 6); //{a: 5, b: 6}
Also in ES6 for even shortened version:
const filterValue = (obj, key, value)=> obj.find(v => v[key] === value);
This method only return the first value which match..., for better result and browser support, you can use filter
:
const filterValue = (obj, key, value)=> obj.filter(v => v[key] === value);
and we will return [{a: 5, b: 6}]
...
This method will return an array instead...
You simpley use for loop as well, create a function like this:
function filteredArray(arr, key, value) {
const newArray = [];
for(i=0, l=arr.length; i<l; i++) {
if(arr[i][key] === value) {
newArray.push(arr[i]);
}
}
return newArray;
}
and call it like this:
filteredArray(jsObjects, "b", 6); //[{a: 5, b: 6}]