This question already has answers here:
Multiple assignment in JavaScript? What does `[ a, b, c ] = [ 1, 2, 3 ]` mean?
(4 answers)
Closed 5 years ago.
Take the following line of code
const [component] = router.getMatchedComponents({ ...to })
Could anyone advise what the square brackets around component means here? I have tried to google this but struggling to find an answer
It's called Destructuring assignment, and it's used to unpack the values of an array and assign them to new variables.
So here in your code:
const [component] = router.getMatchedComponents({ ...to })
You are assigning to the component variable the first element held in the array that will be returned by router.getMatchedComponents({...to}), where to is an array-like structure turned into object using the spread operation.
Related
This question already has answers here:
Syntax - what does square brackets around a variable declaration mean [duplicate]
(1 answer)
Multiple assignment in JavaScript? What does `[ a, b, c ] = [ 1, 2, 3 ]` mean?
(4 answers)
Javascript. Assign array values to multiple variables? [duplicate]
(2 answers)
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.
This question already has answers here:
What does this symbol mean in JavaScript?
(1 answer)
Multiple assignment in JavaScript? What does `[ a, b, c ] = [ 1, 2, 3 ]` mean?
(4 answers)
Closed 9 months ago.
This is what confuses me alot:
When we give a variable a for an example a empty string we do it like this:
const empty = ""
But for useState we do it like this:
const [color, setColor] = useState("Black")
But why? I get so confused that the syntax for useState looks like that.
And ofc searching did not help me.
This question already has answers here:
Multiple assignment in JavaScript? What does `[ a, b, c ] = [ 1, 2, 3 ]` mean?
(4 answers)
What is destructuring assignment and its uses?
(3 answers)
Closed 2 years ago.
Can someone explain me what is going on here?
const [counter, setCounter] = useState(0);
Is it some kind of assignment?
I think you might need to take a look into the React Hooks docs
It's a destructuring assignment on the results of calling the useState function:
the first element of the array is the value
the second element is a function to change value.
This question already has answers here:
How to get all key in JSON object (javascript)
(7 answers)
Closed 2 years ago.
I have a varible, if I print it out, I see this output:
Well, if I'd know the number '118', it would be easy, but in the program where I am using it, I don't know it. So is there any mode to get it without knowing that value?
You could use the Object.keys function to retrieve all keys of your object.
The Object.keys returns an array, you can then access the first element of that array like any other array.
const JSONString = '{"118": {"input1": 6, "input2": 1, "input3": 3}}';
const json = JSON.parse(JSONString);
const keys = Object.keys(json);
console.log(keys[0]);
This question already has answers here:
Multiple assignment in JavaScript? What does `[ a, b, c ] = [ 1, 2, 3 ]` mean?
(4 answers)
Closed 5 years ago.
Take the following line of code
const [component] = router.getMatchedComponents({ ...to })
Could anyone advise what the square brackets around component means here? I have tried to google this but struggling to find an answer
It's called Destructuring assignment, and it's used to unpack the values of an array and assign them to new variables.
So here in your code:
const [component] = router.getMatchedComponents({ ...to })
You are assigning to the component variable the first element held in the array that will be returned by router.getMatchedComponents({...to}), where to is an array-like structure turned into object using the spread operation.