- Any declaration of “var” at any scope level is global, whereas the scope can be block-scoped, where the term “block” can be described as code that is enclosed in flower braces.
- The variable is not lexical in scope but instead is a general scope while let is a block scope. This can be explicit or implicit based on the position of the let statement. If the let statement is within the scope of the block, it is lexical scoping.
- Within the scope within the scope of the windows objects, the variables var can be used. However, statements declared variables can’t apply in this case.
- It is not safe to use the same type of identifiers that are declared with the let statement, as will result in a case that differs for declared variables.
- When it comes to performance comparisons Var is more efficient and let is slower within the loops when it is it is running or running the code.
- Re-declaring var declared as a variable within the same function or scope can cause Syntax Error, whereas a declared variable can’t be declared again.
- The confusion and mistakes caused by value overriding within the scope are avoided using the variables that are declared and advised to use whenever feasible and not always in all cases.
|Definition||Var is an old declaration method for variable||Let’s take a look at the recently introduced form of variable declaration|
|Declaration||It is possible to declare it anyplace and the variable can be carried||It is possible to declare anyplace and is limited to limit boundaries|
|Accessibility||Global access||Access to scopes blocked or lexical scopeing|
|Mode||If it is in the strictest mode, var permits variables to be declared within the same context.||Let’s not allow repetition for the exact variable|
|Browser Support||All browsers can support the var||A few browsers will not support the statement|
|Hoisting||Global variables are elevated||The block-scoped variable is not a hoisted|
|Compatibility||It is supported by all browsers and runtime environments for JS||Transpilers, such as Babel can be used to convert it into older versions that can be used to support across all browsers.|
The declaration of variables using “let” will cause the variable to be accessible across the enclosed scope, causing the identifier to be declared and then used in the block expression scope or statement. Var isn’t able to be replaced by let since it has its own uses across various areas. Let is only used when blocks are of the utmost importance and hoisting isn’t needed in the execution context.