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Are variables defined inside an inner function that have the same name as a variable in an outer function isolated from the outer variable?
function() {
var myTest = "hi there";
( function( myTest ) {
myTest = "goodbye!";
} )();
console.log( myTest ); // myTest should still be "hi there" here, correct?
}
Naturally if I didn't declare myTest inside the inner function it would create a closure and modify the original. I just want to make sure that variables declared within an inner function are always isolated to that function even if their name may conflict with an outer scope.
292
When you declare a variable in a function, you can only access it in the function. These variables are said to be scoped to the function. If you define any inner function within another function, this inner function is called a closure.
Callbacks are functions that are passed into another function as an argument. Closures are functions that are nested in other functions, and it's often used to avoid scope clash with other parts of a JavaScript program.
A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function's scope from an inner function.
Closures refers to scope of variables where as promise are used to 'promise' that an act on something will occur when it is done on an asynchronous action.
Yes, they effectively do. Each function creates a new scope, and the closest scope in which a requested variable is declared always takes precedence. No exceptions.
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