Why is it recommended to use 'let' and 'const' over 'var' in modern JavaScript?
A). 'let' and 'const' are function-scoped
B). 'let' and 'const' prevent variable hoisting
C). 'let' and 'const' are block-scoped, reducing potential errors
D). 'let' and 'const' are faster
What happens when you redeclare a variable with 'var' inside a function?
A). The variable is overwritten
B). The variable declaration is ignored
C). It throws an error
D). The function's scope is reset
What will happen if you declare a 'let' variable inside a block and try to access it outside the block?
A). It will return undefined
B). It will throw a ReferenceError
C). It will return null
D). It will be accessible outside the block
How does 'let' differ from 'var' in terms of scope?
A). 'let' is function-scoped, 'var' is block-scoped
B). Both 'let' and 'var' are block-scoped
C). 'let' is block-scoped, 'var' is function-scoped
D). Both 'let' and 'var' are function-scoped
What error is thrown when attempting to redeclare a 'const' variable?
A). TypeError
B). ReferenceError
C). SyntaxError
D). RangeError
Which of the following correctly describes variable hoisting with 'var'?
A). 'var' declarations are not hoisted
B). Only the variable declaration is hoisted, not the initialization
C). Both declaration and initialization are hoisted
D). Only in strict mode 'var' declarations are hoisted
Can you redeclare a 'let' variable in the same scope in JavaScript?
A). Yes
B). No
C). Only in strict mode
D). Only in non-strict mode
Given 'var a = 1; var a = 2;', what is the value of 'a' after these statements execute?
A). 1
B). 2
C). Undefined
D). Syntax Error
Which of the following is a characteristic of 'const' variables?
A). They can be redeclared
B). They can be reassigned
C). They cannot be redeclared but can be reassigned
D). They cannot be redeclared or reassigned
What happens if you try to redeclare a 'const' variable in JavaScript?
A). It will throw an error
B). The variable is overwritten
C). The variable is converted to 'let'
D). The program continues with a warning