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Learn how to use closures to create private variables in JavaScript. A closure is a function that can access the parent scope, even after the parent function has closed. See examples, explanations and exercises.
- Lexical scoping. Consider the following example code: js function init() { var name = "Mozilla"; // name is a local variable created by init function displayName() { // displayName() is the inner function, that forms the closure console.log(name); // use variable declared in the parent function } displayName(); } init();
- Closure. Consider the following code example: js function makeFunc() { const name = "Mozilla"; function displayName() { console.log(name); } return displayName; } const myFunc = makeFunc(); myFunc();
- Practical closures. Closures are useful because they let you associate data (the lexical environment) with a function that operates on that data. This has obvious parallels to object-oriented programming, where objects allow you to associate data (the object's properties) with one or more methods.
- Emulating private methods with closures. Languages such as Java allow you to declare methods as private, meaning that they can be called only by other methods in the same class.
Jun 5, 2024 · Learn what closure is, how it works, and why it is useful in JavaScript. See examples of creating closures, accessing outer variables, and using closures for state, private variables, and callbacks.
Feb 18, 2020 · A closure is the combination of a function and the lexical environment (scope) within which that function was declared. Closures are a fundamental and powerful property of Javascript.
Learn what closures are and how they work in JavaScript with examples. Closures are functions that have access to the outer scope variables even after the outer function has closed.
As you may have read in the article Variable scope, closure, a variable starts in the “uninitialized” state from the moment when the execution enters a code block (or a function). And it stays uninitalized until the corresponding let statement.
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In JavaScript, a closure is a function that references variables in the outer scope from its inner scope. The closure preserves the outer scope inside its inner scope. To understand the closures, you need to know how the lexical scoping works first.
