How do you call a function from another function in javascript?

I just want to know how to call a javascript function inside another function. If I have the code below, how do I call the second function inside the first?

function function_one()
{
alert("The function called 'function_one' has been called.")
//Here I would like to call function_two.
}

function function_two()
{
alert("The function called 'function_two' has been called.")
}

SandPiper

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asked Dec 24, 2010 at 7:26

Web_DesignerWeb_Designer

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function function_one() {
    function_two(); // considering the next alert, I figured you wanted to call function_two first
    alert("The function called 'function_one' has been called.");
}

function function_two() {
    alert("The function called 'function_two' has been called.");
}

function_one();

A little bit more context: this works in JavaScript because of a language feature called "variable hoisting" - basically, think of it like variable/function declarations are put at the top of the scope (more info).

answered Dec 24, 2010 at 7:28

ChristianChristian

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2

function function_one() {
  function_two(); 
}

function function_two() {
//enter code here
}

Diganta

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answered Nov 13, 2012 at 11:25

0

function function_one()
{
    alert("The function called 'function_one' has been called.")
    //Here u would like to call function_two.
    function_two(); 
}

function function_two()
{
    alert("The function called 'function_two' has been called.")
}

Icarus

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answered Aug 24, 2016 at 13:09

function function_first() {
    function_last(); 
    alert("The function called 'function_first' has been called.");
}

function function_last() {
    alert("The function called 'function_last' has been called.");
}

function_first();

answered Nov 30, 2021 at 12:01

Method Reuse

With the call() method, you can write a method that can be used on different objects.

All Functions are Methods

In JavaScript all functions are object methods.

If a function is not a method of a JavaScript object, it is a function of the global object (see previous chapter).

The example below creates an object with 3 properties, firstName, lastName, fullName.

Example

const person = {
  firstName:"John",
  lastName: "Doe",
  fullName: function () {
    return this.firstName + " " + this.lastName;
  }
}

// This will return "John Doe":
person.fullName();

Try it Yourself »

In the example above, this refers to the person object.

this.firstName means the firstName property of this.

Same as:

this.firstName means the firstName property of person.

What is this?

In JavaScript, the this keyword refers to an object.

Which object depends on how this is being invoked (used or called).

The this keyword refers to different objects depending on how it is used:

The JavaScript call() Method

The call() method is a predefined JavaScript method.

It can be used to invoke (call) a method with an owner object as an argument (parameter).

With call(), an object can use a method belonging to another object.

This example calls the fullName method of person, using it on person1:

Example

const person = {
  fullName: function() {
    return this.firstName + " " + this.lastName;
  }
}
const person1 = {
  firstName:"John",
  lastName: "Doe"
}
const person2 = {
  firstName:"Mary",
  lastName: "Doe"
}

// This will return "John Doe":
person.fullName.call(person1);

Try it Yourself »

This example calls the fullName method of person, using it on person2:

Example

const person = {
  fullName: function() {
    return this.firstName + " " + this.lastName;
  }
}
const person1 = {
  firstName:"John",
  lastName: "Doe"
}
const person2 = {
  firstName:"Mary",
  lastName: "Doe"
}

// This will return "Mary Doe"
person.fullName.call(person2);

Try it Yourself »

The call() Method with Arguments

The call() method can accept arguments:

Example

const person = {
  fullName: function(city, country) {
    return this.firstName + " " + this.lastName + "," + city + "," + country;
  }
}

const person1 = {
  firstName:"John",
  lastName: "Doe"
}

person.fullName.call(person1, "Oslo", "Norway");

Try it Yourself »

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Can we use function inside function in JavaScript?

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What are 3 ways to call a function in JS?