SOLOLEARN JAVASCRIPT CHALLENGE QUESTION... 🤔

Question

Why does this throw an error?
class A {
for(var i=0; i<3; i++)
console.log(i);
}
var x = new A();
//output:
//UncaughtSyntaxError: unexpected token 'var'
//Line: 2
https://www.sololearn.com/post/1468443/?ref=app

Answer 1

Lisa
in fact, if you do not have a constructor method, JavaScript will add an invisible and empty constructor method.
https://www.w3schools.com/jsref/jsref_constructor_class.asp

Answer 2

Javascript classes operate in strict mode that's why it will throw some errors.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes

Answer 3

Yes Lisa, that's the idea behind it.
https://code.sololearn.com/cHDmHG69fCtJ/?ref=app

Answer 4

Of course as said the body of class operates in strict mode means the syntax should be valid, you can leave the constructor empty but in a legal accepted class syntax.

Answer 5

I am not sure but I suppose that it has to do with the fact that the loop does not run in a constructor or method

Answer 6

Kapama, Joshua okay, thanks.
But then the constructor will be empty, right? The for loop would still run out of a constructor or method...
If I put the loop in a constructor, there is no error
class A {
constructor() {
for(var i=0; i<3; i++)
console.log(i);
}
}
var x = new A();

Answer 7

Kapama, Joshua && Lisa:
Thanks a lot guys 👌🏾

Answer 8

Kapama, Joshua:
Thanks a lot. You are most helpful.

Answer 9

Kapama, Joshua:
It means therefore that, explicitly declaring properties etc in the class (and not in a method or constructor) is prohibited in this strict mode right?
Is there a list of permitted syntaxes in a class' strict mode?

Answer 10

Its because u did not add a constructor function, you can leave it empty but its best practise to define variables and functions within jt

Answer 11

Thanks Goke Ekundayo 👍🏼

Answer 12

👑 Tchybooxuur! Happy to help

Answer 13

Let a=[1, 3,5][2];
Let b={x:4,y:10}.y;
Let c="199" [0];
Console.log(a+b+c) ;
What is output of above code..explain in detail.. Can anyone explain me plzzzz