This question already has answers here:
One-liner to take some properties from object in ES 6
(12 answers)
ES6 - Destructuring assignment - Unpack some properties from existing object to a new object? [duplicate]
(3 answers)
Closed 4 years ago.
let x = {
a: 10,
b: 20,
c: 30
};
Is there any way to make only a,b keys of x as another object?
let y = x; //someway here through Object destructing
console.log(y); //{a:10,b:20}
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Syntax - what does square brackets around a variable declaration mean [duplicate]
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Multiple assignment in JavaScript? What does `[ a, b, c ] = [ 1, 2, 3 ]` mean?
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Javascript. Assign array values to multiple variables? [duplicate]
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Closed 8 months ago.
Consider the declarations of variable "x" and "y"
const x = 1;
const [y] = [1]
What is the meaning of 2nd declaration?
Can someone suggest an article about such declaration type.
This is destructuring assignment.
You are unpacking values from arrays or object properties.
In your above code, a const variable y will be defined with value 1.
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How to determine equality for two JavaScript objects?
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How to explain object references in ECMAScript terms?
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Javascript Object Identities
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If I do:
const o1 = {};
const o2 = {};
is it guaranteed that o1===o2 is false?
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Explain this javascript code
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JavaScript code trick: What's the value of foo.x
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Multiple assignment confusion
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Closed 3 years ago.
I have this kind of construction
let a = {x: 1}
let b = a
a.x = a = {y: 2}
How you can explain in details how I get these results ?
a.x = undefined
a={y: 2}
b={x: {y: 2}}
This question already has answers here:
Does JavaScript guarantee object property order?
(13 answers)
Does ES6 introduce a well-defined order of enumeration for object properties?
(3 answers)
Closed 3 years ago.
I understand that in JS Object keys aren't guaranteed to be ordered.
However, I find that for object literals the order, after creation, remains equal to the literal unless I add a new key.
Could I rely on the key ordering of an object literal I freeze?
For instance:
const o = Object.freeze({
a: 1,
b: 2,
c: 3
});
What are the conditions under which the order of this object's keys wouldn't be a,b,c?
This question already has answers here:
What’s the difference between “{}” and “[]” while declaring a JavaScript array?
(8 answers)
Closed 4 years ago.
The point of confusion is - when we check the type of array or object using typeof get the return value as Object. So what's the main difference between them.
You can check using constructor.name
const myArr = []
const myObj = {}
console.log(`myArr is an ${myArr.constructor.name}`)
console.log(`my Obj is an ${myObj.constructor.name}`)