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What is the difference between closure and nested functions in JavaScript?
JavaScript Closures
In JavaScript, all functions work like closures. A closure is a function, which uses the scope in which it was declared when invoked. It is not the scope in which it was invoked.
Here’s an example
<!DOCTYPEhtml>
<html>
<body>
<h2>JavaScriptClosures</h2>
<script>
varp = 20;
functiona(){
var p = 40;
b(function(){
alert(p);
});
}
functionb(f){
var p = 60;
f();
}
a();
</script>
</body>
</html>JavaScript nested functions
JavaScript 1.2 allows function definitions to be nested within other functions as well.Still, there is a restriction that function definitions may not appear within loops or conditionals. These restrictions on function definitions apply only to function declarations with the function statement.
Example
You can try to run the following example to learn how to implement nested functions
<html>
<head>
<script>
<!--
functionhypotenuse(a,b) {
functionsquare(x){returnx*x;}
returnMath.sqrt(square(a)+square(b));
}
functionsecondFunction() {
varresult;
result=hypotenuse(5,4);
document.write(result );
}
//-->
</script>
</head>
<body>
<p>Clickthe following button to call the function</p>
<form>
<inputtype="button"onclick="secondFunction()"value="CallFunction">
</form>
<p>Usedifferent parameters inside the function and then try...</p>
</body>
</html>
Updated on: 09-Jan-2020
706 Views
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