How to call nested function in javascript?

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I have two function like this..

function a() {
  function b() {
    alert('reached');
  }
}

how i call function b() from outside of function a()..

In general, you can't. The point of defining a function inside another function is to scope it to that function.

The only way for b to be accessible outside of a is if (when you call a) you do something inside a to make it available outside of a.

This is usually done to create a closure, so that b could access variables from a while not making those variables public. The normal way to do this is to return b.

function a() {
  var c = 0;
  function b() {
    alert(c++);
  }
  return b;
}
var d = a();
d();
d();
d();
var e = a();
e();
e();
e();

How to call nested function from outside function, function robin(){ a.hello(); }. I suggest working through some basic JavaScript tutorials and/or books in order to get a good understanding of how� Prior to JavaScript 1.2, function definition was allowed only in top level global code, but 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.

You can rearange your code to this

function a() {
   this.b = function() {
   alert('reached');
 }
}

now instantiate it and run:

c = new a();
c.b();

JavaScript, JavaScript | Nested functions. Write one function inside another function. Make a call to the inner function in the return statement of the outer function. Call it fun(a)(b) where a is parameter to outer and b is to the inner function. Finally return the combined output from the nested function. If we call any other function inside the function is clearly said to be Nested function. Syntax: Function getName() //outer function {getAge();//inner function} Function getAge() {//code} getName(); //function calling. Explanation: getName() is called nested function because t has one more function getAge() inside the function.

You will need to return the inner function call.

function a() {
  function b() {
    alert('reached');
  }
  return b();
}

And then you can call this function simply by calling function a like this:

a();

The output will be the required alert.

JavaScript - Nested Functions, JavaScript - Nested Functions - Prior to JavaScript 1.2, function definition was " Call Function"> </form> <p>Use different parameters inside the function and� Nested functions have interesting scoping rules. A nested function can access any variables and parameters of the outer function(s). In our example above, you can see that the nested function – diameter – is passed the radius parameter which is a parameter defined by the outer function named circumference.

JavaScript Nested Functions, A brief introduction to nested functions in JavaScript; accessing inner The inner () function can also be called by using another set of parentheses while calling� Write one function inside another function. Make a call to the inner function in the return statement of the outer function. Call it fun (a) (b) where a is parameter to outer and b is to the inner function. Finally return the combined output from the nested function.

Variable scope, Every function is meant to output its number. remains the same no matter from where you call this returned nested function. JavaScript Nested Functions. All functions have access to the global scope. In fact, in JavaScript, all functions have access to the scope "above" them. JavaScript supports nested functions. Nested functions have access to the scope "above" them. In this example, the inner function plus() has access to the counter variable in the parent function:

JavaScript Functions, Function expressions are invoked by calling the variable name with a pair of parentheses containing JavaScript functions can be nested within other functions. People affectionately call this pattern the callback hell. It kinda looks like this: firstFunction(args, function() { secondFunction(args, function() { thirdFunction(args, function() { // And so on… }); }); }); This is JavaScript for you. It’s mind-boggling to see nested callbacks, but I don’t think it’s a “hell”.

Comments
  • You can't. b is only defined inside the scope of a.
  • Some very good answers in this related post here.
  • there is no need to return the return-value of b when you just wanna call it