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Why do variable in an inner function return nan when there is the same variable name at the inner function declared after log
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What's happening here? I get a different result if I declare a variable after console.log in the inner function
I understand that var has a functional scope and inner function can access the variable from their parent
function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log NaN
var a = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log 3
var b = 8
}
inner()
}
outer()The log returns NaN in the first example and log 3 in the second example
javascript function
edited 59 mins ago
Nick Parsons
10.3k2926
asked 1 hour ago
ClaudeClaude
476
add a comment |
What's happening here? I get a different result if I declare a variable after console.log in the inner function
I understand that var has a functional scope and inner function can access the variable from their parent
function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log NaN
var a = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log 3
var b = 8
}
inner()
}
outer()The log returns NaN in the first example and log 3 in the second example
javascript function
edited 59 mins ago
Nick Parsons
10.3k2926
asked 1 hour ago
ClaudeClaude
476
add a comment |
What's happening here? I get a different result if I declare a variable after console.log in the inner function
I understand that var has a functional scope and inner function can access the variable from their parent
function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log NaN
var a = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log 3
var b = 8
}
inner()
}
outer()The log returns NaN in the first example and log 3 in the second example
javascript function
edited 59 mins ago
Nick Parsons
10.3k2926
asked 1 hour ago
ClaudeClaude
476
What's happening here? I get a different result if I declare a variable after console.log in the inner function
I understand that var has a functional scope and inner function can access the variable from their parent
function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log NaN
var a = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log 3
var b = 8
}
inner()
}
outer()The log returns NaN in the first example and log 3 in the second example
function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log NaN
var a = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log NaN
var a = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log 3
var b = 8
}
inner()
}
outer()function outer() {
var a = 2;
function inner() {
a++;
console.log(a) //log 3
var b = 8
}
inner()
}
outer()javascript function
javascript function
edited 59 mins ago
Nick Parsons
10.3k2926
asked 1 hour ago
ClaudeClaude
476
edited 59 mins ago
Nick Parsons
10.3k2926
asked 1 hour ago
ClaudeClaude
476
edited 59 mins ago
Nick Parsons
10.3k2926
edited 59 mins ago
Nick Parsons
10.3k2926
edited 59 mins ago
Nick Parsons
10.3k2926
10.3k2926
asked 1 hour ago
ClaudeClaude
476
asked 1 hour ago
ClaudeClaude
476
asked 1 hour ago
ClaudeClaude
476
476
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
This is due to hoisting
The declaration of a in the inner function is hoisted to the top of the function, overriding the outer function's a, so a is undefined
undefined++ returns NaN, hence your result.
Your code is equivalent to:
function outer() {
var a=2;
function inner() {
var a;
a++;
console.log(a); //log NaN
a = 8;
}
inner();
}
outer();
Rewriting your code in this way makes it easy to see what's going on.
edited 49 mins ago
Shidersz
9,3362933
answered 1 hour ago
jrojro
582115
add a comment |
Because var is hoisted through the function, you're essentially running undefined++ which is NaN. If you remove var a = 8 in inner, the code works as expected:
function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
add a comment |
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
var a=0;
function outer(){
a=2;
function inner(){
a=a+1;
console.log(a)
a = 8
}
inner()
}
outer()
answered 59 mins ago
Darshit ShahDarshit Shah
53
3
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
This is due to hoisting
The declaration of a in the inner function is hoisted to the top of the function, overriding the outer function's a, so a is undefined
undefined++ returns NaN, hence your result.
Your code is equivalent to:
function outer() {
var a=2;
function inner() {
var a;
a++;
console.log(a); //log NaN
a = 8;
}
inner();
}
outer();
Rewriting your code in this way makes it easy to see what's going on.
edited 49 mins ago
Shidersz
9,3362933
answered 1 hour ago
jrojro
582115
add a comment |
This is due to hoisting
The declaration of a in the inner function is hoisted to the top of the function, overriding the outer function's a, so a is undefined
undefined++ returns NaN, hence your result.
Your code is equivalent to:
function outer() {
var a=2;
function inner() {
var a;
a++;
console.log(a); //log NaN
a = 8;
}
inner();
}
outer();
Rewriting your code in this way makes it easy to see what's going on.
edited 49 mins ago
Shidersz
9,3362933
answered 1 hour ago
jrojro
582115
add a comment |
This is due to hoisting
The declaration of a in the inner function is hoisted to the top of the function, overriding the outer function's a, so a is undefined
undefined++ returns NaN, hence your result.
Your code is equivalent to:
function outer() {
var a=2;
function inner() {
var a;
a++;
console.log(a); //log NaN
a = 8;
}
inner();
}
outer();
Rewriting your code in this way makes it easy to see what's going on.
edited 49 mins ago
Shidersz
9,3362933
answered 1 hour ago
jrojro
582115
This is due to hoisting
The declaration of a in the inner function is hoisted to the top of the function, overriding the outer function's a, so a is undefined
undefined++ returns NaN, hence your result.
Your code is equivalent to:
function outer() {
var a=2;
function inner() {
var a;
a++;
console.log(a); //log NaN
a = 8;
}
inner();
}
outer();
Rewriting your code in this way makes it easy to see what's going on.
edited 49 mins ago
Shidersz
9,3362933
answered 1 hour ago
jrojro
582115
edited 49 mins ago
Shidersz
9,3362933
edited 49 mins ago
Shidersz
9,3362933
edited 49 mins ago
Shidersz
9,3362933
9,3362933
answered 1 hour ago
jrojro
582115
answered 1 hour ago
jrojro
582115
answered 1 hour ago
jrojro
582115
582115
add a comment |
add a comment |
Because var is hoisted through the function, you're essentially running undefined++ which is NaN. If you remove var a = 8 in inner, the code works as expected:
function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
add a comment |
Because var is hoisted through the function, you're essentially running undefined++ which is NaN. If you remove var a = 8 in inner, the code works as expected:
function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
add a comment |
Because var is hoisted through the function, you're essentially running undefined++ which is NaN. If you remove var a = 8 in inner, the code works as expected:
function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
Because var is hoisted through the function, you're essentially running undefined++ which is NaN. If you remove var a = 8 in inner, the code works as expected:
function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();function outer() {
var a = 2;
function inner() {
a++;
console.log(a);
}
inner();
}
outer();answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
answered 59 mins ago
Jack BashfordJack Bashford
13.8k31848
13.8k31848
add a comment |
add a comment |
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
var a=0;
function outer(){
a=2;
function inner(){
a=a+1;
console.log(a)
a = 8
}
inner()
}
outer()
answered 59 mins ago
Darshit ShahDarshit Shah
53
3
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
add a comment |
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
var a=0;
function outer(){
a=2;
function inner(){
a=a+1;
console.log(a)
a = 8
}
inner()
}
outer()
answered 59 mins ago
Darshit ShahDarshit Shah
53
3
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
add a comment |
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
var a=0;
function outer(){
a=2;
function inner(){
a=a+1;
console.log(a)
a = 8
}
inner()
}
outer()
answered 59 mins ago
Darshit ShahDarshit Shah
53
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
var a=0;
function outer(){
a=2;
function inner(){
a=a+1;
console.log(a)
a = 8
}
inner()
}
outer()
answered 59 mins ago
Darshit ShahDarshit Shah
53
edited 9 mins ago
answered 59 mins ago
Darshit ShahDarshit Shah
53
answered 59 mins ago
Darshit ShahDarshit Shah
53
answered 59 mins ago
Darshit ShahDarshit Shah
53
53
3
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
add a comment |
3
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
3
3
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
How does this piece of code explains the issue? Can you provide an explanation of the code you have posted?
– Shidersz
52 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
They can’t access the inner function value so we have to defined globally. After globally you can use A value anywhere in the code
– Darshit Shah
50 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. From Review
– double-beep
11 mins ago
add a comment |
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