Aladdin :
I saw this code on the site w3schools.com (JavaScript Best Practices)
// Declare at the beginning
var i;
// Use later
for (i = 0; i < 5; i++) {
I don’t understand why declaring this variable is considered good practice. It is needed only for the cycle. Why should i make it global
Elias Soares :
Actually, this code is outdated. The best practice is to use let
instead of var
(see this question on StackOverflow, and declare it inside the for statement:
for (let i = 0; i < 5; i++) {
console.log(i); // 0, 1, 2, 3, 4
}
console.log(i); // undefined variable i
The let
defines a block scoped variable. This variable won't "bubble" up to the global scope, being more efficient by not polluting the global scope.
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