Tell us what’s happening:
In the previous lession we have been told :
Variables which are declared without the let or const keywords are automatically created in the global scope.
If I define myVar in function myLocalScope() below without using ‘let’ or ‘const’, wouldn’t it be automatically global ?
Your code so far
function myLocalScope() {
// Only change code below this line
myVar=9; //like here without using let or const keyword.
console.log('inside myLocalScope', myVar);
}
myLocalScope();
// Run and check the console
// myVar is not defined outside of myLocalScope
console.log('outside myLocalScope', myVar);
why wouldn’t console.log print 9 if it is in global space ?
Challenge: Basic JavaScript - Local Scope and Functions
Hey there
No matter the scope you will still have to declare it. Other than that, no it would not make it global, here are some good infos on scopes: Javascript scopes
In previous lesson:" Global scope and functions"
I had code:
// Declare the myGlobal variable below this line
let myGlobal=10;
function fun1() {
// Assign 5 to oopsGlobal here
oopsGlobal=5;
}
// Only change code above this line
function fun2() {
let output = "";
if (typeof myGlobal != "undefined") {
output += "myGlobal: " + myGlobal;
}
if (typeof oopsGlobal != "undefined") {
output += " oopsGlobal: " + oopsGlobal;
}
console.log(output);
}
Here oopsGlobal is defined in fun1 without let/const keywords but it still can be used inside fun2 , isn’t it because we haven’t used let/const keywords ?
So you are right, I wasnt looking closely enough. For some reason I didnt register what you were asking lol. Yeah, so if you look at the link posted earlier you will see the automatically global example.
fun1 doesn’t have return value so I am guessing console.fun1 probably shouldn’t be getting the correct output .
However the point i am trying to ask is that even if fun2 is checking whether oopsGlobal is not undefined it still knows the there is a variable oopsGlobal outside scope of fun1 and it’s not giving the error like “oopsGlobal is not defined”
The correct output of the previous code I gave in previous post is:
I checked , but then why the below code isn’t working like why second console isn’t giving 9 and instead giving “myVar not defined” isn’t myVar global so it should be giving output as ‘outside myLocalScope 9’
function myLocalScope() {
// Only change code below this line
myVar=9; //like here without using let or const keyword.
console.log('inside myLocalScope', myVar);
}
myLocalScope();
// Run and check the console
// myVar is not defined outside of myLocalScope
console.log('outside myLocalScope', myVar);
Correct me if I am wrong:
I have copied your previous code where you write:
oopsGlobal=5;
I have renamed it to ooops
I have deleted that line
and it still checks if oopsGlobal is undefined, so for me it means it does not neccesseraly mean that it knows that some undeclared name exists, but it checks for it. But as said, correct me if I am mistaken
even if it checks for all variables regardless if they are defined or not it’s still giving output in console as
oopsGlobal: 5
so it does uses the value defined in fun1 taken it as global and reuses it in fun2 to get the output.
Also in link from your first post there is a section on automatically global.
Automatically Global
If you assign a value to a variable that has not been declared, it will automatically become a GLOBAL variable.
This code example will declare a global variable carName, even if the value is assigned inside a function.
Code:
myFunction();
// code here can use carName
function myFunction() {
carName = "Volvo";
}
Here carName is global variable even though it is defined in myFunction scope.
That is not always true. Undeclared variables are prohibited in “strict mode”, which freeCodeCamp uses in all of our JS curriculum because it prevents learners from writing certain types of bugs (like this very one).
like why second console isn’t giving 9 and instead giving “myVar not defined” isn’t myVar global so it should be giving output as ‘outside myLocalScope 9’
