Are let variables hoisted?

Technically, var , let and const are hoisted. var is declared and initialized during hoisting. let and const are only declared during hoisting, not initialized. Accessing uninitialized variables result in ReferenceError .

Are let variables hoisted in JavaScript?

Yes, variables declared with let and const are hoisted. Where they differ from other declarations in the hoisting process is in their initialization. During the compilation phase, JavaScript variables declared with var and function are hoisted and automatically initialized to undefined .

Does let hoisting?

Hoisting of let

Just like var , let declarations are hoisted to the top. Unlike var which is initialized as undefined , the let keyword is not initialized. So if you try to use a let variable before declaration, you’ll get a Reference Error .

Are function expressions hoisted?

Function expressions in JavaScript are not hoisted. Therefore, you cannot use function expressions before defining them. This is all there is to be kept in mind for creating functions from a hoisting point of view.

Should I use VAR or let?

The main difference between the two though is that let deals with block scope whereas var deals with global scope or function scope depending on where it’s declared. As long as your variable isn’t declared within any function, var can be used again anywhere else in your code.

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How do you prevent hoisting?

Some ways to avoid hoisting are:

  1. Use let or const — As explained above, using let or const instead of var would throw an exception and not let the program run, hence helping catch the issue earlier.
  2. Use function expressions instead of function declarations.

How do you do function expressions?

A function expression can be stored in a variable: var x = function (a, b) {return a * b}; After a function expression has been stored in a variable, the variable can be used as a function.

What is == and === in JavaScript?

= is used for assigning values to a variable in JavaScript. == is used for comparison between two variables irrespective of the datatype of variable. === is used for comparision between two variables but this will check strict type, which means it will check datatype and compare two values.

What is function expression?

A function expression is very similar to and has almost the same syntax as a function declaration (see function statement for details). The main difference between a function expression and a function declaration is the function name, which can be omitted in function expressions to create anonymous functions.

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