Generally defining a function inside another function is to scope it to that function and you can’t call a nested function in JavaScript.
function a() {
function b() {
alert('reached');
}
}You have to do something inside function to make the inner function available outside it. You will need to return the inner function call.
function a() {
function b() {
alert('reached');
}
return b();
}
Then you can call this function simply by calling the function a like this:
a();Call a nested function in JavaScript
A simple example code calls function b() from outside of function a().
<!DOCTYPE html>
<html>
<body>
<script>
function f1() {
var c = 0;
function f2() {
console.log(c++);
}
return f2;
}
var d = f1();
d();
d();
d();
var e = f1();
e();
e();
</script>
</body>
</html>
Output:
Call nested function from outside function
You can’t call it from anywhere else unless you make it available somehow, for instance by assigning it to a property on the object you’re creating by calling batman via new:
function batman(){
this.hello = function() {
console.log("hello world!");
};
}
Comment if you have any doubts or suggestions on this JS function topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version