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?
{ console.log(b); let b = 20; }
A). 20
B). undefined
C). null
D). ReferenceError
How can you avoid variable hoisting issues with let
?
A). Declare variables at the bottom of the code
B). Use var
instead
C). Declare variables at the top of their scope
D). Do not declare variables
Which of the following is true about let
declarations?
A). They are hoisted and initialized at the top of their scope
B). They are hoisted but not initialized
C). They are not hoisted at all
D). They are function scoped
What is the scope of a variable declared with let
inside a loop?
A). Global scope
B). Function scope
C). Block scope
D). Module scope
What is the 'temporal dead zone'?
A). The period during which a variable is declared but not yet initialized
B). The time when the variable is accessible throughout the program
C). The period after variable initialization
D). None of the above
What will be the output of the following code?
for (let i = 0; i < 3; i++) { setTimeout(() => console.log(i), 0); }
A). 0 0 0
B). 3 3 3
C). 0 1 2
D). ReferenceError
What will be the output of the following code?
let e = 25; function test() { console.log(e); let e = 30; } test();
A). 25
B). 30
C). undefined
D). ReferenceError
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
What happens when you try to re-declare a let
variable in the same scope?
A). It reassigns the value
B). It throws a SyntaxError
C). It re-declares the variable
D). It throws a TypeError