Answer & Solution
let declarations are hoisted and the variable is in the TDZ until the declaration is executed, so it logs undefined.
let d; console.log(d); d = 15;
let declarations are hoisted and the variable is in the TDZ until the declaration is executed, so it logs undefined.
What will be the output of the following code?
console.log(a); let a = 10;
A). undefined
B). 10
C). null
D). ReferenceError
What will be the output of the following code?
let c = 5; { let c = 10; console.log(c); }
A). 5
B). 10
C). ReferenceError
D). undefined
Which statement about let and const is correct?
A). Both are block scoped, but only let can be re-assigned
B). Both are block scoped, but only const can be re-assigned
C). Only const is block scoped
D). Both are not block scoped
What is the difference between let and var in terms of scope?
A). let is function scoped, var is block scoped
B). let is block scoped, var is function scoped
C). Both are function scoped
D). Both are block scoped
Which keyword should be used to declare variables that do not get re-assigned?
A). let
B). const
C). var
D). function
Where should let variables be declared to avoid TDZ issues?
A). At the top of the global scope
B). At the bottom of their block scope
C). At the top of their block scope
D). Anywhere in the code
What will be the output of the following code?
let i = 50; { let i = 55; console.log(i); } console.log(i);
A). 50 50
B). 55 50
C). 50 55
D). ReferenceError
What will be the output of the following code?
{ console.log(b); let b = 20; }
A). 20
B). undefined
C). null
D). ReferenceError
What will be the output of the following code?
let h = 40; { console.log(h); h = 45; } console.log(h);
A). 40 45
B). 45 45
C). undefined undefined
D). ReferenceError 45
What will be the output of the following code?
let f = 10; if (true) { console.log(f); let f = 20; }
A). 10
B). 20
C). undefined
D). ReferenceError