Javascript pass variable outside function

Javascript How To Extract A Value Outside Function With Code Examples

In this article, we will see how to solve Javascript How To Extract A Value Outside Function with examples.

/* Not putting "var", "let" or "const" will make the variable Public
And usable outside a functin */

function Play(){
  	Video = 12 // Seconds
	var Length = 15
}
console.log(Video) // Prints 12
console.log(Length) // "Lenght" is undefined

We have shown how to address the Javascript How To Extract A Value Outside Function problem by looking at a number of different cases.

How do you access a variable outside a function in JavaScript?

To access a variable outside a function in JavaScript make your variable accessible from outside the function. First, declare it outside the function, then use it inside the function. You can’t access variables declared inside a function from outside a function.26-May-2022

How do you take the value out of a for loop?

have an hidden element say an input. set the value of it inside the loop with your value desired. call the change event along for the input element. Add a event listener for the change of input and get that value which is obviously outside the loop.15-Feb-2017

Can I declare variable outside function JavaScript?

Variables declared Globally (outside any function) have Global Scope. Global variables can be accessed from anywhere in a JavaScript program. Variables declared with var , let and const are quite similar when declared outside a block.

Is it possible to access the data outside the subroutine?

You can not access the variables inside the function unless it is declared outside it.29-Mar-2012

How do you use local variables outside a function?

Variables declared inside any function with var keyword are called local variables. Local variables cannot be accessed or modified outside the function declaration. Function parameters are considered as local variables.

How do you use a variable inside a function outside the function?

you have to declare the variable outside the function to use it. variables declared inside a function can only be accessed inside that function. think of each function as a box and the lid can only be opened from inside: the function can grab what’s outside or put something out, but you can’t reach in its box.31-Jan-2017

How can I get data outside a forEach loop in JavaScript?

Just use the array outside of data. map(…); and inside getParticipant(conf_url, function(data) {…}); . I guess, this is an asynchronous function, so you kinda have to do it this way.19-Aug-2015

How do you return a value from a while loop in Java?

You can return only once. The problem is that every method must always have a return statement. In the code above you only return inside the loop if you find a matching result.There are various approach to this problem.

• Use while loop.
• Use for loop with additional stop condition.
• Use break key word.

What is difference between Forin and for OF in JavaScript?

The only difference between them is the entities they iterate over: for..in iterates over all enumerable property keys of an object. for..of iterates over the values of an iterable object.26-Mar-2015

What is curry in JavaScript?

Currying is a function that takes one argument at a time and returns a new function expecting the next argument. It is a transformation of functions that translates a function from callable as f(a, b, c) into callable as f(a)(b)(c).26-Aug-2021

Scope refers to the availability of variables and functions in certain parts of the code.

In JavaScript, a variable has two types of scope:

1. Global Scope
2. Local Scope

Global Scope

A variable declared at the top of a program or outside of a function is considered a global scope variable.

Let's see an example of a global scope variable.

// program to print a text 
let a = "hello";

function greet () {
    console.log(a);
}

greet(); // hello

In the above program, variable a is declared at the top of a program and is a global variable. It means the variable a can be used anywhere in the program.

The value of a global variable can be changed inside a function. For example,

// program to show the change in global variable
let a = "hello";

function greet() {
    a = 3;
}

// before the function call
console.log(a);

//after the function call
greet();
console.log(a); // 3

In the above program, variable a is a global variable. The value of a is hello. Then the variable a is accessed inside a function and the value changes to 3.

Hence, the value of a changes after changing it inside the function.

Note: It is a good practice to avoid using global variables because the value of a global variable can change in different areas in the program. It can introduce unknown results in the program.

In JavaScript, a variable can also be used without declaring it. If a variable is used without declaring it, that variable automatically becomes a global variable.

For example,

function greet() {
    a = "hello"
}

greet();

console.log(a); // hello

In the above program, variable a is a global variable.

If the variable was declared using let a = "hello", the program would throw an error.

Note: In JavaScript, there is "strict mode"; in which a variable cannot be used without declaring it. To learn more about strict, visit JavaScript Strict.

Local Scope

A variable can also have a local scope, i.e it can only be accessed within a function.

Example 1: Local Scope Variable

// program showing local scope of a variable
let a = "hello";

function greet() {
    let b = "World"
    console.log(a + b);
}

greet();
console.log(a + b); // error

Output

helloWorld
Uncaught ReferenceError: b is not defined

In the above program, variable a is a global variable and variable b is a local variable. The variable b can be accessed only inside the function greet. Hence, when we try to access variable b outside of the function, an error occurs.

let is Block Scoped

The let keyword is block-scoped (variable can be accessed only in the immediate block).

Example 2: block-scoped Variable

// program showing block-scoped concept
// global variable
let a = 'Hello';

function greet() {

    // local variable
    let b = 'World';

    console.log(a + ' ' + b);

    if (b == 'World') {

        // block-scoped variable
        let c = 'hello';

        console.log(a + ' ' + b + ' ' + c);
    }

    // variable c cannot be accessed here
    console.log(a + ' ' + b + ' ' + c);
}

greet();

Output

Hello World
Hello World hello
Uncaught ReferenceError: c is not defined

In the above program, variable

• a is a global variable. It can be accessed anywhere in the program.
• b is a local variable. It can be accessed only inside the function greet.
• c is a block-scoped variable. It can be accessed only inside the if statement block.

Hence, in the above program, the first two console.log() work without any issue.

However, we are trying to access the block-scoped variable c outside of the block in the third console.log(). This will throw an error.

Note: In JavaScript, var is function scoped and let is block-scoped. If you try to use var c = 'hello'; inside the if statement in the above program, the whole program works, as c is treated as a local variable.

To learn more about let versus var, visit JavaScript let vs var.

How do you call a variable outside a function?

Can we declare variable outside function?

Which variable declared outside a function in JavaScript?

What is $scope in JavaScript?