Mar 9, 2017 · In essence, I am trying to declare a variable in the condition-part of a while loop in javascript: while (var b=a.pop()) { do_sth(b) } Yet, my browser (firefox) doesn't accept that. Instead I have to go like so: var b while (b=a.pop()) { do_sth(b) } which works. Is this behaviour expected?

Apr 12, 2015 · It Doesn't make difference if you declare variables inside or outside of for loop. Below is the sample code to test.

Aug 27, 2013 · Variables declared with var are not local to the loop, i.e. they are in the same scope the for loop is in. Variables declared with let are local to the statement. The result of this expression is discarded.

Aug 20, 2024 · Variables that are created inside a function are local variables, and local variables can only be referred to by the code within the function. Variables created outside of functions are global variables, and the code in all functions has access to all global variables.

When deciding whether to declare variables inside or outside a loop in JavaScript, it is essential to consider the specific requirements of the code and weigh the advantages and disadvantages of each approach.

If the variable is declared outside the loop, then it has the global scope as it can be used through-out the function and inside of the loop too. If the variable is declared inside the loop, then the scope is only valid inside the loop and if used outside the loop will give an error.

Local variables have Function Scope: They can only be accessed from within the function. Since local variables are only recognized inside their functions, variables with the same name can be used in different functions.

Nov 13, 2023 · Variables Declared in Local Scope. Variables in local scope are typically declared within functions, conditional statements, loops, or other code blocks. These variables are, in essence, "local" to that block of code, and they cannot be directly accessed from outside it.

Apr 28, 2020 · We know that due to hoisting in JavaScript, the var keyword only supports function scope. let on the other hand, allows block-scoped variables. But how exactly does scoping work for for loops?

In JavaScript for loop I can use var keyword in loop definition something like that: for (var i=0; i<10; i++) ... I know scope of the variable i is not inside the loop but inside function where loop is declared.