Can let be hoisted in JavaScript?

Can let be 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 .

Is Let better than VAR?

The main difference is the scope difference, while let can be only available inside the scope it's declared, like in for loop, var can be accessed outside the loop for example. From the documentation in MDN (examples also from MDN):

Is Let Necessary?

The first thing we've learnt is that for most purposes, var and let aren't strictly necessary in JavaScript. Roughly speaking, scoping constructs with lexical scope can be mechanically transformed into functional arguments. ... If we take let away and only use var , we have to add IIFEs to get block scope.

What is hoisting in JavaScript MDN?

JavaScript Hoisting refers to the process whereby the compiler allocates memory for variable and function declarations prior to execution of the code. Declarations that are made using var are initialized with a default value of undefined . Declarations made using let and const are not initialized as part of hoisting.

Why is let not hoisted?

let and const are only declared during hoisting, not initialized. Accessing uninitialized variables result in ReferenceError . Prefer let over var , wherever possible to avoid the confusion arising due to hoisting.

Why does JavaScript use hoisting?

In JavaScript, Hoisting is the default behavior of moving all the declarations at the top of the scope before code execution. Basically, it gives us an advantage that no matter where functions and variables are declared, they are moved to the top of their scope regardless of whether their scope is global or local.

Should I use const var or let?

Summary. As a general rule, you should always declare variables with const, if you realize that the value of the variable needs to change, go back and change it to let. Use let when you know that the value of a variable will change. Use const for every other variable.

Why we should not use VAR?

In Javascript, it doesn't matter how many times you use the keyword “var”. If it's the same name in the same function, you are pointing to the same variable. ... They both work with block scope, which means, if variables or constants are declared inside a block, they will not be available to the “parent” blocks.

Is const faster than let?

It appears that using const would inherently make code a little faster, because it seems to reduce the amount of hoisting necessary. Take the following, basic example: ... While it appears trivial, if let and const are actually faster, then that would be a strong argument for consistently using them.

Why is let and const not hoisted?

let and const are only declared during hoisting, not initialized. Accessing uninitialized variables result in ReferenceError . Prefer let over var , wherever possible to avoid the confusion arising due to hoisting.

Are there variables declared with let or const hoisted?

• Within a scope, constshould have been made to be hoisted and just-in-time-initialized when it is accessed. Really, they should have a const, a let, and another keyword which creates a variable that works like a "readonly" let.

What do you need to know about hoisting in JavaScript?

• To understand this, you have to understand the term "hoisting". Hoisting is JavaScript's default behavior of moving all declarations to the top of the current scope (to the top of the current script or the current function). Variables and constants declared with let or const are not hoisted! Read more about let and const in JS Let / Const.

How are variables hoisted to the top of a block?

• Variables defined with let and const are hoisted to the top of the block, but not initialized. Meaning: The block of code is aware of the variable, but it cannot be used until it has been declared. Using a let variable before it is declared will result in a ReferenceError.

Which is an example of a definition of hoisting?

• Conceptually, for example, a strict definition of hoisting suggests that variable and function declarations are physically moved to the top of your code, but this is not in fact what happens. Instead, the variable and function declarations are put into memory during the compile phase, but stay exactly where you typed them in your code.