CODEWITHSUNDEEP
javascript
Anthony
Anthony

Reputation: 97

Global variable inside a function cant be access outside

If I understood it correctly, declaring a variable without using the keyword var inside a function will create a global scoped variable.

But I am getting this "ReferenceError: oopsGlobal is not defined" when accessing the variable from outside its container function.

,,,
 // Declare the myGlobal variable below this line
var myGlobal = 10 

function fun1() {
  // Assign 5 to oopsGlobal Here
  oopsGlobal = 5
}

// Only change code above this line

function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

console.log(oopsGlobal) // ReferenceError: oopsGlobal is not defined
,,,

Upvotes: 0

Views: 116

Answers (2)

shreyasm-dev
shreyasm-dev

Reputation: 2844

That is happening because you are never actually running fun1(). If you don't call a function, the code inside will never be executed.

ReferenceError:

 // Declare the myGlobal variable below this line
var myGlobal = 10 

function fun1() {
  // Assign 5 to oopsGlobal Here
  oopsGlobal = 5
}

// Only change code above this line

function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

console.log(oopsGlobal) // ReferenceError: oopsGlobal is not defined


No ReferenceError (note that fun1() is called before console.log())

 // Declare the myGlobal variable below this line
var myGlobal = 10 

function fun1() {
  // Assign 5 to oopsGlobal Here
  oopsGlobal = 5
}

// Only change code above this line

function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

fun1()
console.log(oopsGlobal)

Upvotes: 1

Chase
Chase

Reputation: 3116

You have written code, but never INVOKED it. fun1 and fun2 are never run. I added one line below that invokes the fun1() function which causes the assignment to happen.

This is more of an answer to provide a demonstration -- more than likely you do NOT want to actually write code that has global variables or side-effects like this. If you are writing software for the browser, using window or globalThis to store you global state also may make it more clear as well.

// Declare the myGlobal variable below this line
var myGlobal = 10 

function fun1() {
  // Assign 5 to oopsGlobal Here
  oopsGlobal = 5
}

fun1(); // You wrote the functions previous, but you never CALLED them.

// Only change code above this line

function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

console.log(oopsGlobal) // ReferenceError: oopsGlobal is not defined

Upvotes: 0

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