what is closure in javascript
function OuterFunction() {
var outerVariable = 100;
function InnerFunction() {
alert(outerVariable);
}
return InnerFunction;
}
var innerFunc = OuterFunction();what is closure in javascript
function OuterFunction() {
var outerVariable = 100;
function InnerFunction() {
alert(outerVariable);
}
return InnerFunction;
}
var innerFunc = OuterFunction();What is Closures in JavaScript
/*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. In JavaScript, closures are
created every time a function is created, at function creation time.*/
function init() {
var name = 'Mozilla'; // name is a local variable created by init
function displayName() { // displayName() is the inner function, a closure
alert(name); // use variable declared in the parent function
}
displayName();
}
init();closure in javascript
var counter = (function() {
var privateCounter = 0;
function changeBy(val) {
privateCounter += val;
}
return {
increment: function() {
changeBy(1);
},
decrement: function() {
changeBy(-1);
},
value: function() {
return privateCounter;
}
};
})();
console.log(counter.value()); // logs 0
counter.increment();
counter.increment();
console.log(counter.value()); // logs 2
counter.decrement();
console.log(counter.value()); // logs 1syntax of closures
/*
{ (parameters) -> return type in
body
}
*/
var numbers = [1, 2, 3, 4]
var reversed = numbers.sorted(by: {(a: Int, b: Int) -> Bool in
return a > b
})A closure Function
var returns_a_func = function () {
var word = 'I can see inside ' function sentence(){ var word2 = 'I can also see outside. ' console.log(word + 'and ' + word2) } return sentence;
}var finalSentence = returns_a_func()finalSentence()JavaScript - Closures
function makeAdder(x) {
return function(y) {
return x + y;
};
}
var add5 = makeAdder(5);
var add10 = makeAdder(10);
console.log(add5(2)); // 7
console.log(add10(2)); // 12
//=====
//add5 and add10 are both closures.
//They share the same function body definition, but store different lexical environments.
//In add5's lexical environment, x is 5, while in the lexical environment for add10, x is 10.Copyright © 2021 Codeinu
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