const monsters = {
'1': {
name: 'godzilla',
age: 250000000
},
'2': {
Name: 'manticore',
age: 21
}
}
I learn JavaScript from Codecademy, What does this code mean?
Is this two dimensional array? If not, what is it?
The data structure you are showing in your code example is not an array at all, it is an object. Arrays are defined using square brackets ([]) and their keys (indices) are not explicitly declared but rather assigned automatically.
So if you wrote your code like this, for example, you would have an array containing objects:
const monsters = [
{
name: 'godzilla',
age: 250000000
},
{
name: 'manticore',
age: 21
}
]
…so you could access the values by their array index, like so.
monsters[0].name; // godzilla
monsters[1].name; // manticore
Related
This question already has an answer here:
Lodash uniqBy update the latest value
(1 answer)
Closed 9 months ago.
I am working on one project where I need to remove duplicate values from JSON array object with some specification in react JS. I have tried to remove using _.uniqBy but in the output it took very first value from duplicate value which is I don't want.
Suppose You have an array JSON like:
[ { id: 1, name: 'bob' }, { id: 2, name: 'bill' }, { id: 1, name: 'alice' } ]
using _.uniqBy I got [ { id: 1, name: 'bob' }, { id: 2, name: 'bill' }] this output.
but I want [ { id: 2, name: 'bill' }, { id: 1, name: 'alice' } ] this output.
As you can see I want output whose name is alice not bob along with id:1.
Can anyone help me?
Thank you.
My first thought is to use a reduce, and shove the items in a map, then get the values:
Object.values(items.reduce((map, item) => ({ ...map, [item.id]: item }), {}))
This is probably not very efficient though if you're dealing with large arrays of have performance concerns.
It's a quick and dirty one-liner. If you want something more efficient I'd take a look at the lodash source code and tweak it to your needs or write something similar:
https://github.com/lodash/lodash/blob/2f79053d7bc7c9c9561a30dda202b3dcd2b72b90/.internal/baseUniq.js
This question already has answers here:
How to determine if Javascript array contains an object with an attribute that equals a given value?
(27 answers)
Closed 3 years ago.
let's say I have an array of objects:
let arr = [
{
name: 'Jack',
id: 1
},
{
name: 'Gabriel',
id: 2
},
{
name: 'John',
id: 3
}
]
I need to check whether that array includes the name 'Jack' for example using:
if (arr.includes('Jack')) {
// don't add name to arr
} else {
// push name into the arr
}
but arr.includes('Jack') returns false, how can I check if an array of objects includes the name?
Since you need to check the object property value in the array, you can try with Array.prototype.some():
The some() method tests whether at least one element in the array passes the test implemented by the provided function. It returns a Boolean value.
let arr = [
{
name: 'Jack',
id: 1
},
{
name: 'Gabriel',
id: 2
},
{
name: 'John',
id: 3
}
]
var r = arr.some(i => i.name.includes('Jack'));
console.log(r);
I have an array with a few objects inside. Each object contains a few properties.
I use vue.js v-for method to render it in the list.
But I cannot render it in the specific order of the given property. I use this function to sort it ascending:
evenNumbers: function () {
return this.numbers.sort(function (a, b) { return a - b });
}
It works fine with a simple array like [22, 1, 2, 3, 4, 5]. But it does not work for the objects like this:
numbers2: [
{
name: 'Alan',
age: 72
},
{
name: 'Thomas',
age: 32
},
{
name: 'Thomas',
age: 32
},
{
name: 'Michal',
age: 32
},
]
}
I want to sort them by the age in the ascending order.
At the end I want to render them inside the li for example only {{ age }} property.
Here is a snippet with my code:
https://jsfiddle.net/marektchas/jyznx475/2/
Since you now have complex objects, sorting by the object directly won't work as you expect (the operator runs some implicit conversions resulting in NaN for every comparison).
You must sort by the specific property, in this case, age. So:
evenNumbers2: function () {
return this.numbers2.sort(function (a, b) { return a.age - b.age });
}
See updated fiddle.
This question already has an answer here:
Map and Sort in one iteration in Javascript?
(1 answer)
Closed 4 years ago.
I'm doing unit testing using javascript testing framework (mocha, chai, etc). How can I assert my array of objects using its name?
I can successfully sort this using localeCompare but I'm not getting what I wanted on my test. It just returns 1 or -1.
Here's my a sample of what I want to sort.
var Stuffs = [
{ name: "PWE", address: "1234567890" },
{ name: "NSA", address: "1234567890" },
{ name: "AVE", address: "1234567890" },
{ name: "QRE", address: "1234567890" },
]
How can I assert this to ["AVE", "NSA", "PWE", "QRE"] ?
To get your desired Array, you can use:
Stuffs.map(({ name }) => name).sort();
You could also use reduce() method of array and then sort().
DEMO
var Stuffs = [{ name: "PWE", address: "1234567890" },
{ name: "NSA", address: "1234567890" },
{ name: "AVE", address: "1234567890" },
{ name: "QRE", address: "1234567890" }];
let sortedArr = Stuffs.reduce((r,{name})=>r.concat(name),[]).sort((a,b)=>a.localeCompare(b));
console.log(sortedArr);
Using chai
assert.deepInclude(Stuffs, {name: "AVE"});
assert.deepInclude(Stuffs, {name: "NSA"});
assert.deepInclude(Stuffs, {name: "QRE"});
assert.deepInclude(Stuffs, {name: "PWE"});
Edit: I may have misunderstood it to mean, how can assert that the array has those values.
First you would need a sorted array to compare it to. The original array needs to be cloned (shallow is fine for this) since sort will modify the array it is called on. Using from to generate the clone, we can then alphabetically sort the new array to get the desired order.
const sortedStuffs = Array.from(stuffs).sort(({name: a}, {name: b}) => a.localeCompare(b));
Finally using every, we can compare the names for each element to see if they match. As soon as one fails, the returned value will be false
stuffs.every(({name}, i) => name === sortedStuffs[i].name);
Full working example:
const stuffs = [
{name: "PWE", address: "1234567890"},
{name: "NSA", address: "1234567890"},
{name: "AVE", address: "1234567890"},
{name: "QRE", address: "1234567890"}
];
const sortedStuffs = Array.from(stuffs).sort(({name: a}, {name: b}) => a.localeCompare(b));
const isSorted = stuffs.every(({name}, i) => name === sortedStuffs[i].name);
console.log(isSorted);
could someone give me some direction on how to write a piece of JSON text in JavaScript. eg
{
"Header.MainsiteURL": "http://www.ford.es",
"Header.backToMainsiteMobile": "ES-Main site"
}
You can declare a single Json object using the following syntax.
var person = {
Name: "NameOfPerson",
Age: 23
}
The following is a Json array for storing people's names and age.
var people = [
{
Name: "NameOfPerson",
Age: 23
},{
Name: "NameOfAnotherPerson",
Age: 12
}
]
What you seem to be missing in your example are the properties of the object.