does the while loop have no block-level scope like the for loop
if I define a human variable in the while loop, will the variable be cleared before I continue to operate in the previously defined variable in the next loop
does the while loop have no block-level scope like the for loop
if I define a human variable in the while loop, will the variable be cleared before I continue to operate in the previously defined variable in the next loop
1. We can think that expressions with {} are block-level scope, provided that with let const, variables defined by var do not have block-level scope.
2. Let's take a look at the comparison: var is used in
while to declare variables :
a
let:
We found that using the let declaration, the value printed for the first time is undefined, indicating that the value of b in each loop is a new value ( block-level scope takes effect ), and an error is reported when printing the value of b outside the loop, indicating that the variable b is not available outside {}. indicates that the block-level scope takes effect again.
if you have any questions, please leave a message.
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