Local variables cannot be accessed outside the functions in which they are declared.

Scope of Variables

A scope is a region of the program and broadly speaking there are three places, where variables can be declared:

Here let us explain what local and global variables are.

Variables that are declared inside a function or block are local variables. They can be used only by statements that are inside that function or block of code. Local variables are not known to functions outside their own. Following is the example using local variables:

#include <iostream>
using namespace std;
 
int main ()
{
  // Local variable declaration:
  int a, b;
  int c;
 
  // actual initialization
  a = 10;
  b = 20;
  c = a + b;
 
  cout << c;
 
  return 0;
}

Global variables are defined outside of all the functions, usually on top of the program. The global variables will hold their type throughout the life-time of your program.

A global variable can be accessed by any function. That is, a global variable is available for use throughout your entire program after its declaration. Following is the example using global and local variables:

#include <iostream>
using namespace std;
 
// Global variable declaration:
int g;
 
int main ()
{
  // Local variable declaration:
  int a, b;
 
  // actual initialization
  a = 10;
  b = 20;
  g = a + b;
 
  cout << g;
 
  return 0;
}

A program can have same name for local and global variables but value of local variable inside a function will take preference. For example:

#include <iostream>
using namespace std;
 
// Global variable declaration:
int g = 20;
 
int main ()
{
  // Local variable declaration:
  int g = 10;
 
  cout << g;
 
  return 0;
}

When the above code is compiled and executed, it produces the following result:

10

What is Local Variable in Javascript

Local variables are variables that can only be accessed within the function or block statement that they have been declared in. Block statements include if, if else, while, for and do while.

Declare Local Variable in Javascript

You can use var, let, and const keywords to create local variables within a function.

function functionWithLocalVariable(){
  var username ="OscarKittyKat";
  const name="Oscar Wilden";
  let estimatedWorth2022 = 2585000;
}

functionWithLocalVariable();

If you log the variables inside the function, you will get their values.

Code

function functionWithLocalVariable(){
  var username ="OscarKittyKat";
  const name="Oscar Wilden";
  let estimatedWorth2022 = 2585000;
  console.log(username);
  console.log(name);
  console.log(estimatedWorth2022);
}

functionWithLocalVariable();

Result

These variables cannot be accessed outside the function. A quick check using a console log shows the variable as not defined outside of the function.

function functionWithLocalVariable(){
  var username ="OscarKittyKat";
  const name="Oscar Wilden";
  let estimatedWorth2022 = 2585000;
}

functionWithLocalVariable();
console.log(username);
console.log(name);
console.log(estimatedWorth2022);

Result

To create local variables within a block, you can use only use let and const keywords. Block scope was introduced in the ES6 Javascript version. You can use the power of block scope with if, if else, while, for and do while statements.

var age = 17;
if(age<18){
  const designation = "Child";
} else {
  const designation = "Adult";
}

The variables cannot be accessed outside the block. Checking the variable designation using a console log shows the variable as not defined outside the if else block but gives a result of child when read inside the block it is declared in.

var age = 17;
if(age<18){
  const designation = "Child";
  console.log(designation);
} else {
  const designation = "Adult";
  console.log(designation);
}
console.log(designation);

Result

Example of Local Variable in Javascript

Local Variable Within Function and Block Example

function getWordExistInPage(){
  let totalpages = 2;
  for(let page=0; page<totalpages; page++){
    console.log(page);
    console.log(totalpages);

  }
  console.log(totalpages);
  console.log(page);
}
getWordExistInPage();
console.log(totalpages);

page is a local block scope variable inside for loop while totalpages is a local function scope variable inside function getWordExistInPage.

You can only read the value of page within the for loop while you can only read the value of totalpages inside the function getWordExistInPage.

Result

How to Access Local Variable in Javascript

To get access to local variables in Javascript, you can make a function call within the function that has the variables and pass the variable as a function parameter.

Example

function functionWithLocalVariable(){
  let localVariable = "I am a local Variable Being passed to another function";
  functionThatUsesTheLocalVariable(localVariable);
}

function functionThatUsesTheLocalVariable(variable){
  console.log(variable);
}

functionWithLocalVariable();

Result

how to Access Local Variable Outside Function in Javascript

You can pass local variable to another function by making the variable the return value of the function.

When you call the function within another function this new function will get the value of the variable.

Example

function functionWithReturnValue(){
  let independenceYear = 1963;
  return independenceYear;
}

function getHowManyYearsSinceIndependence(){
  let yearsSinceIndependence = 2022 - functionWithReturnValue());
  console.log(yearsSinceIndependence);
}

getHowManyYearsSinceIndependence();

Result

Difference Between Local and Global Variable in Javascript

Global variables can be accessed by any part of you code on that file while local variables can only be accessed by code within the function or block they are declared in.

You can read my on global variable and how to create variables in Javascript.

Hi there! I am Avic Ndugu.

I have published 100+ blog posts on HTML, CSS, Javascript, React and other related topics. When I am not writing, I enjoy reading, hiking and listening to podcasts.

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