Javascript - scoping an incrementing-loop counter only to that loop












-3















I've run into this error multiple times now, and wondering if there's a way to have the code auto control for it?



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var length = other_array.length

  for (var i = 0; i < length; i ++ ) {

    // some code

  }

}


The code above doesn't run properly because the inner i and length carry over to the outer level code. So to actually make it work, I have to manually set different variables to manage the scoping. I.e., something like the below works:



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var s_length = other_array.s_length

  for (var s_i = 0; s_i < length; s_i ++ ) {

    // some code

  }

}


But of course, it's hard to always remember when an inner function has another loop in it. Wondering if there's a way to control it so that loop variables are always only constrained to THAT loop itself.






javascript







share|improve this question




















  • 3





    Take a look at the let keyword.

    – ggorlen
    Nov 26 '18 at 2:21






  • 2





    The code above doesn't run properly because the inner i and length carry over to the outer level no, they don't - you must be doing something else wrong

    – Jaromanda X
    Nov 26 '18 at 2:40


















-3















I've run into this error multiple times now, and wondering if there's a way to have the code auto control for it?



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var length = other_array.length

  for (var i = 0; i < length; i ++ ) {

    // some code

  }

}


The code above doesn't run properly because the inner i and length carry over to the outer level code. So to actually make it work, I have to manually set different variables to manage the scoping. I.e., something like the below works:



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var s_length = other_array.s_length

  for (var s_i = 0; s_i < length; s_i ++ ) {

    // some code

  }

}


But of course, it's hard to always remember when an inner function has another loop in it. Wondering if there's a way to control it so that loop variables are always only constrained to THAT loop itself.






javascript







share|improve this question




















  • 3





    Take a look at the let keyword.

    – ggorlen
    Nov 26 '18 at 2:21






  • 2





    The code above doesn't run properly because the inner i and length carry over to the outer level no, they don't - you must be doing something else wrong

    – Jaromanda X
    Nov 26 '18 at 2:40
















-3












-3








-3








I've run into this error multiple times now, and wondering if there's a way to have the code auto control for it?



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var length = other_array.length

  for (var i = 0; i < length; i ++ ) {

    // some code

  }

}


The code above doesn't run properly because the inner i and length carry over to the outer level code. So to actually make it work, I have to manually set different variables to manage the scoping. I.e., something like the below works:



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var s_length = other_array.s_length

  for (var s_i = 0; s_i < length; s_i ++ ) {

    // some code

  }

}


But of course, it's hard to always remember when an inner function has another loop in it. Wondering if there's a way to control it so that loop variables are always only constrained to THAT loop itself.






javascript







share|improve this question
















I've run into this error multiple times now, and wondering if there's a way to have the code auto control for it?



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var length = other_array.length

  for (var i = 0; i < length; i ++ ) {

    // some code

  }

}


The code above doesn't run properly because the inner i and length carry over to the outer level code. So to actually make it work, I have to manually set different variables to manage the scoping. I.e., something like the below works:



var length = some_array.length

for (var i = 0; i < length; i ++) {

  someMethod(some_array[i].name) 

}



function someMethod(name) {

  var s_length = other_array.s_length

  for (var s_i = 0; s_i < length; s_i ++ ) {

    // some code

  }

}


But of course, it's hard to always remember when an inner function has another loop in it. Wondering if there's a way to control it so that loop variables are always only constrained to THAT loop itself.






javascript




javascript






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 26 '18 at 2:21









ggorlen

7,6483926




7,6483926










asked Nov 26 '18 at 2:19









jamesjames

1,72732859




1,72732859








  • 3





    Take a look at the let keyword.

    – ggorlen
    Nov 26 '18 at 2:21






  • 2





    The code above doesn't run properly because the inner i and length carry over to the outer level no, they don't - you must be doing something else wrong

    – Jaromanda X
    Nov 26 '18 at 2:40
















  • 3





    Take a look at the let keyword.

    – ggorlen
    Nov 26 '18 at 2:21






  • 2





    The code above doesn't run properly because the inner i and length carry over to the outer level no, they don't - you must be doing something else wrong

    – Jaromanda X
    Nov 26 '18 at 2:40










3




3





Take a look at the let keyword.

– ggorlen
Nov 26 '18 at 2:21





Take a look at the let keyword.

– ggorlen
Nov 26 '18 at 2:21




2




2





The code above doesn't run properly because the inner i and length carry over to the outer level no, they don't - you must be doing something else wrong

– Jaromanda X
Nov 26 '18 at 2:40







The code above doesn't run properly because the inner i and length carry over to the outer level no, they don't - you must be doing something else wrong

– Jaromanda X
Nov 26 '18 at 2:40














2 Answers
2






active

oldest

votes


















0














This is why let keyword is a better option than var- it keeps the scope to just the function or method that calls it.



The following snippet consoles - 



0 / test 1 / 0 / test a

0 / test 1 / 1 / test b

1 / test 2 / 0 / test a

1 / test 2 / 1 / test b


ie: for each item of some_array - it calls someMethod and consoles the name of the first array as well as each iteration of the second array (other_array).






let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}








share|improve this answer





















  • 1





    I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

    – Mark Meyer
    Nov 26 '18 at 2:32













  • Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

    – gavgrif
    Nov 26 '18 at 2:40











  • So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

    – Mark Meyer
    Nov 26 '18 at 2:48



















0














SCOPE



In JavaScript there are two types of scope:



Local scope
Global scope
JavaScript has function scope: Each function creates a new scope.



let allows you to declare variables that are limited in scope to the block.
Notice how var create a property on the global object but let is undefined.



var x = 'global';

let y = 'global';

console.log(this.x); // "global"

console.log(this.y); // undefined


Let's try it with your code.



let some_array = [{ name: 'Angel' }, { name: 'James' }]

let other_array = ['0','1'];



//let i is declared local

for (let i = 0; i < some_array.length; i++) {

    someMethod(some_array[i].name) //"let" some_array variable is required here to the local "for loop" scope.

}



function someMethod(name) {

//let i is declared local here again so it's considered a new variable i.

    for (let i = 0; i < some_array.length; i++) {

        console.log(name)

    }

}


For more examples about scope in Javascript






share|improve this answer
























  • Wouldn't var i also be local to someMethod()?

    – Mark Meyer
    Nov 26 '18 at 2:50











  • @MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

    – Angel Roma
    Nov 26 '18 at 2:55











  • That's not quite correct. Inside a function var is scoped to that function.

    – Mark Meyer
    Nov 26 '18 at 3:01











  • var keyword defines a variable globally regardless of block scope.

    – Angel Roma
    Nov 26 '18 at 3:06











  • But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

    – Mark Meyer
    Nov 26 '18 at 3:11











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









0














This is why let keyword is a better option than var- it keeps the scope to just the function or method that calls it.



The following snippet consoles - 



0 / test 1 / 0 / test a

0 / test 1 / 1 / test b

1 / test 2 / 0 / test a

1 / test 2 / 1 / test b


ie: for each item of some_array - it calls someMethod and consoles the name of the first array as well as each iteration of the second array (other_array).






let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}








share|improve this answer





















  • 1





    I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

    – Mark Meyer
    Nov 26 '18 at 2:32













  • Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

    – gavgrif
    Nov 26 '18 at 2:40











  • So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

    – Mark Meyer
    Nov 26 '18 at 2:48
















0














This is why let keyword is a better option than var- it keeps the scope to just the function or method that calls it.



The following snippet consoles - 



0 / test 1 / 0 / test a

0 / test 1 / 1 / test b

1 / test 2 / 0 / test a

1 / test 2 / 1 / test b


ie: for each item of some_array - it calls someMethod and consoles the name of the first array as well as each iteration of the second array (other_array).






let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}








share|improve this answer





















  • 1





    I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

    – Mark Meyer
    Nov 26 '18 at 2:32













  • Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

    – gavgrif
    Nov 26 '18 at 2:40











  • So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

    – Mark Meyer
    Nov 26 '18 at 2:48














0












0








0







This is why let keyword is a better option than var- it keeps the scope to just the function or method that calls it.



The following snippet consoles - 



0 / test 1 / 0 / test a

0 / test 1 / 1 / test b

1 / test 2 / 0 / test a

1 / test 2 / 1 / test b


ie: for each item of some_array - it calls someMethod and consoles the name of the first array as well as each iteration of the second array (other_array).






let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}








share|improve this answer















This is why let keyword is a better option than var- it keeps the scope to just the function or method that calls it.



The following snippet consoles - 



0 / test 1 / 0 / test a

0 / test 1 / 1 / test b

1 / test 2 / 0 / test a

1 / test 2 / 1 / test b


ie: for each item of some_array - it calls someMethod and consoles the name of the first array as well as each iteration of the second array (other_array).






let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}








let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}





let some_array=[{id: '1', name: 'test 1'},{id: '2', name: 'test 2'}];

let other_array=[{id: 'a', name: 'test a'},{id: 'b', name: 'test b'}];



let length = some_array.length;



for (let i = 0; i < length; i ++) {

  someMethod(i, some_array[i].name) 

}



function someMethod(index, name) {

  let length = other_array.length

  for (let i = 0; i < length; i ++ ) {

    console.log(index + ' / ' + name + ' / ' + i + ' / ' + other_array[i].name);

  }

}






share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 26 '18 at 2:39

























answered Nov 26 '18 at 2:24









gavgrifgavgrif

8,6912918




8,6912918








  • 1





    I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

    – Mark Meyer
    Nov 26 '18 at 2:32













  • Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

    – gavgrif
    Nov 26 '18 at 2:40











  • So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

    – Mark Meyer
    Nov 26 '18 at 2:48














  • 1





    I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

    – Mark Meyer
    Nov 26 '18 at 2:32













  • Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

    – gavgrif
    Nov 26 '18 at 2:40











  • So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

    – Mark Meyer
    Nov 26 '18 at 2:48








1




1





I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

– Mark Meyer
Nov 26 '18 at 2:32







I get the same output regardless of let or var here. Maybe there's a better example? i inside someMethod is scoped to the function.

– Mark Meyer
Nov 26 '18 at 2:32















Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

– gavgrif
Nov 26 '18 at 2:40





Each i IS scoped to its location - I just amended it to log the i's as well and as you can see - each log shows its place in the sequence - 0/0 , 0,1 , 1,0 ,11 - or in other words - for each of the i's in the first gtopu its calling the method and in the method - its iteratnig over the second list.

– gavgrif
Nov 26 '18 at 2:40













So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

– Mark Meyer
Nov 26 '18 at 2:48





So, maybe I'm just missing the point. What would be different if you replaced all the lets with vars?

– Mark Meyer
Nov 26 '18 at 2:48













0














SCOPE



In JavaScript there are two types of scope:



Local scope
Global scope
JavaScript has function scope: Each function creates a new scope.



let allows you to declare variables that are limited in scope to the block.
Notice how var create a property on the global object but let is undefined.



var x = 'global';

let y = 'global';

console.log(this.x); // "global"

console.log(this.y); // undefined


Let's try it with your code.



let some_array = [{ name: 'Angel' }, { name: 'James' }]

let other_array = ['0','1'];



//let i is declared local

for (let i = 0; i < some_array.length; i++) {

    someMethod(some_array[i].name) //"let" some_array variable is required here to the local "for loop" scope.

}



function someMethod(name) {

//let i is declared local here again so it's considered a new variable i.

    for (let i = 0; i < some_array.length; i++) {

        console.log(name)

    }

}


For more examples about scope in Javascript






share|improve this answer
























  • Wouldn't var i also be local to someMethod()?

    – Mark Meyer
    Nov 26 '18 at 2:50











  • @MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

    – Angel Roma
    Nov 26 '18 at 2:55











  • That's not quite correct. Inside a function var is scoped to that function.

    – Mark Meyer
    Nov 26 '18 at 3:01











  • var keyword defines a variable globally regardless of block scope.

    – Angel Roma
    Nov 26 '18 at 3:06











  • But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

    – Mark Meyer
    Nov 26 '18 at 3:11
















0














SCOPE



In JavaScript there are two types of scope:



Local scope
Global scope
JavaScript has function scope: Each function creates a new scope.



let allows you to declare variables that are limited in scope to the block.
Notice how var create a property on the global object but let is undefined.



var x = 'global';

let y = 'global';

console.log(this.x); // "global"

console.log(this.y); // undefined


Let's try it with your code.



let some_array = [{ name: 'Angel' }, { name: 'James' }]

let other_array = ['0','1'];



//let i is declared local

for (let i = 0; i < some_array.length; i++) {

    someMethod(some_array[i].name) //"let" some_array variable is required here to the local "for loop" scope.

}



function someMethod(name) {

//let i is declared local here again so it's considered a new variable i.

    for (let i = 0; i < some_array.length; i++) {

        console.log(name)

    }

}


For more examples about scope in Javascript






share|improve this answer
























  • Wouldn't var i also be local to someMethod()?

    – Mark Meyer
    Nov 26 '18 at 2:50











  • @MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

    – Angel Roma
    Nov 26 '18 at 2:55











  • That's not quite correct. Inside a function var is scoped to that function.

    – Mark Meyer
    Nov 26 '18 at 3:01











  • var keyword defines a variable globally regardless of block scope.

    – Angel Roma
    Nov 26 '18 at 3:06











  • But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

    – Mark Meyer
    Nov 26 '18 at 3:11














0












0








0







SCOPE



In JavaScript there are two types of scope:



Local scope
Global scope
JavaScript has function scope: Each function creates a new scope.



let allows you to declare variables that are limited in scope to the block.
Notice how var create a property on the global object but let is undefined.



var x = 'global';

let y = 'global';

console.log(this.x); // "global"

console.log(this.y); // undefined


Let's try it with your code.



let some_array = [{ name: 'Angel' }, { name: 'James' }]

let other_array = ['0','1'];



//let i is declared local

for (let i = 0; i < some_array.length; i++) {

    someMethod(some_array[i].name) //"let" some_array variable is required here to the local "for loop" scope.

}



function someMethod(name) {

//let i is declared local here again so it's considered a new variable i.

    for (let i = 0; i < some_array.length; i++) {

        console.log(name)

    }

}


For more examples about scope in Javascript






share|improve this answer













SCOPE



In JavaScript there are two types of scope:



Local scope
Global scope
JavaScript has function scope: Each function creates a new scope.



let allows you to declare variables that are limited in scope to the block.
Notice how var create a property on the global object but let is undefined.



var x = 'global';

let y = 'global';

console.log(this.x); // "global"

console.log(this.y); // undefined


Let's try it with your code.



let some_array = [{ name: 'Angel' }, { name: 'James' }]

let other_array = ['0','1'];



//let i is declared local

for (let i = 0; i < some_array.length; i++) {

    someMethod(some_array[i].name) //"let" some_array variable is required here to the local "for loop" scope.

}



function someMethod(name) {

//let i is declared local here again so it's considered a new variable i.

    for (let i = 0; i < some_array.length; i++) {

        console.log(name)

    }

}


For more examples about scope in Javascript







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 26 '18 at 2:42









Angel RomaAngel Roma

19829




19829













  • Wouldn't var i also be local to someMethod()?

    – Mark Meyer
    Nov 26 '18 at 2:50











  • @MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

    – Angel Roma
    Nov 26 '18 at 2:55











  • That's not quite correct. Inside a function var is scoped to that function.

    – Mark Meyer
    Nov 26 '18 at 3:01











  • var keyword defines a variable globally regardless of block scope.

    – Angel Roma
    Nov 26 '18 at 3:06











  • But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

    – Mark Meyer
    Nov 26 '18 at 3:11



















  • Wouldn't var i also be local to someMethod()?

    – Mark Meyer
    Nov 26 '18 at 2:50











  • @MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

    – Angel Roma
    Nov 26 '18 at 2:55











  • That's not quite correct. Inside a function var is scoped to that function.

    – Mark Meyer
    Nov 26 '18 at 3:01











  • var keyword defines a variable globally regardless of block scope.

    – Angel Roma
    Nov 26 '18 at 3:06











  • But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

    – Mark Meyer
    Nov 26 '18 at 3:11

















Wouldn't var i also be local to someMethod()?

– Mark Meyer
Nov 26 '18 at 2:50





Wouldn't var i also be local to someMethod()?

– Mark Meyer
Nov 26 '18 at 2:50













@MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

– Angel Roma
Nov 26 '18 at 2:55





@MarkMeyer let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. var is rather a keyword which defines a variable globally regardless of block scope

– Angel Roma
Nov 26 '18 at 2:55













That's not quite correct. Inside a function var is scoped to that function.

– Mark Meyer
Nov 26 '18 at 3:01





That's not quite correct. Inside a function var is scoped to that function.

– Mark Meyer
Nov 26 '18 at 3:01













var keyword defines a variable globally regardless of block scope.

– Angel Roma
Nov 26 '18 at 3:06





var keyword defines a variable globally regardless of block scope.

– Angel Roma
Nov 26 '18 at 3:06













But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

– Mark Meyer
Nov 26 '18 at 3:11





But it doesn't define it globally when used inside a function. In the example you have, it makes no difference whether you use let or var for i because the second one is defined inside the function someMethod. It will be a distinct variable unrelated to the i outside the function. Nothing changes if you use var instead of let in your example.

– Mark Meyer
Nov 26 '18 at 3:11


















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