Overriding the value of const

So I was reading an article and stumbled and saw this CodePen and saw that in increment method it is setting count as const and I'm quite unable to process this, that How can you override const? Can anyone explain what I'm missing?

  state = {

    count: 0

  };



  // Increase count

  increment = () => {

    const { count } = this.state;

    return this.setState({ count: count + 1 });

  };

Why declare const when you can use let or var because usage of const is quite confusing knowing the deconstructed variable is going to be manipulated?

edited Nov 19 '18 at 16:51

asked Nov 19 '18 at 16:27

Yash Karanke

15918

1

It's very unclear what you're asking. The code in the question doesn't have const anywhere and it doesn't "override" anything.
– JJJ
Nov 19 '18 at 16:29

@JJJ it seems like someone edited it. and what part are you unclear about the question?
– Yash Karanke
Nov 19 '18 at 16:38

1) What const are you talking about (there is no const in the code) and 2) what part do you think is "overriding" something?
– JJJ
Nov 19 '18 at 16:40

1

@JJJ it should be clear now edited the question and you can also see the codepen
– Yash Karanke
Nov 19 '18 at 16:41

add a comment |

  state = {

    count: 0

  };



  // Increase count

  increment = () => {

    const { count } = this.state;

    return this.setState({ count: count + 1 });

  };

Why declare const when you can use let or var because usage of const is quite confusing knowing the deconstructed variable is going to be manipulated?

edited Nov 19 '18 at 16:51

asked Nov 19 '18 at 16:27

Yash Karanke

15918

1

It's very unclear what you're asking. The code in the question doesn't have const anywhere and it doesn't "override" anything.
– JJJ
Nov 19 '18 at 16:29

@JJJ it seems like someone edited it. and what part are you unclear about the question?
– Yash Karanke
Nov 19 '18 at 16:38

1) What const are you talking about (there is no const in the code) and 2) what part do you think is "overriding" something?
– JJJ
Nov 19 '18 at 16:40

1

@JJJ it should be clear now edited the question and you can also see the codepen
– Yash Karanke
Nov 19 '18 at 16:41

add a comment |

  state = {

    count: 0

  };



  // Increase count

  increment = () => {

    const { count } = this.state;

    return this.setState({ count: count + 1 });

  };

Why declare const when you can use let or var because usage of const is quite confusing knowing the deconstructed variable is going to be manipulated?

edited Nov 19 '18 at 16:51

asked Nov 19 '18 at 16:27

Yash Karanke

15918

  state = {

    count: 0

  };



  // Increase count

  increment = () => {

    const { count } = this.state;

    return this.setState({ count: count + 1 });

  };

Why declare const when you can use let or var because usage of const is quite confusing knowing the deconstructed variable is going to be manipulated?

reactjs const

edited Nov 19 '18 at 16:51

asked Nov 19 '18 at 16:27

Yash Karanke

15918

edited Nov 19 '18 at 16:51

asked Nov 19 '18 at 16:27

Yash Karanke

15918

edited Nov 19 '18 at 16:51

asked Nov 19 '18 at 16:27

Yash Karanke

15918

asked Nov 19 '18 at 16:27

Yash Karanke

15918

asked Nov 19 '18 at 16:27

Yash Karanke

15918

1

It's very unclear what you're asking. The code in the question doesn't have const anywhere and it doesn't "override" anything.
– JJJ
Nov 19 '18 at 16:29

@JJJ it seems like someone edited it. and what part are you unclear about the question?
– Yash Karanke
Nov 19 '18 at 16:38

1) What const are you talking about (there is no const in the code) and 2) what part do you think is "overriding" something?
– JJJ
Nov 19 '18 at 16:40

1

@JJJ it should be clear now edited the question and you can also see the codepen
– Yash Karanke
Nov 19 '18 at 16:41

add a comment |

1

It's very unclear what you're asking. The code in the question doesn't have const anywhere and it doesn't "override" anything.
– JJJ
Nov 19 '18 at 16:29

@JJJ it seems like someone edited it. and what part are you unclear about the question?
– Yash Karanke
Nov 19 '18 at 16:38

1) What const are you talking about (there is no const in the code) and 2) what part do you think is "overriding" something?
– JJJ
Nov 19 '18 at 16:40

1

@JJJ it should be clear now edited the question and you can also see the codepen
– Yash Karanke
Nov 19 '18 at 16:41

It's very unclear what you're asking. The code in the question doesn't have const anywhere and it doesn't "override" anything.
– JJJ
Nov 19 '18 at 16:29

@JJJ it seems like someone edited it. and what part are you unclear about the question?
– Yash Karanke
Nov 19 '18 at 16:38

1) What const are you talking about (there is no const in the code) and 2) what part do you think is "overriding" something?
– JJJ
Nov 19 '18 at 16:40

@JJJ it should be clear now edited the question and you can also see the codepen
– Yash Karanke
Nov 19 '18 at 16:41

add a comment |

4 Answers
4

active

oldest

votes

The code is not overriding the behavior of const. The increment is happening, not by changing the value of the const count variable, but by calling setState which will replace (asynchronously) the entire state of the component. Then the next time increment or decrement is called, count will receive the new value via the deconstructing assignment from this.state -- that isn't a change to the variable's value, it is a new variable (local to the increment function) each time increment is called.

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

Point taken, but why use const, doesn't it a bit of bad practice given that you know you have to change the state?
– Yash Karanke
Nov 19 '18 at 16:48

1

@YashKaranke Yup, horrible example of using const. There are entire camps of people who believe "use const for everything unless the variable has to be reassigned", which leads to ambiguity and also does not tell the reader what is actually important to not be reassigned vs. what just happens to not be reassigned, but won't hurt anything if it is. It dilutes the meaning of const, kinda like the story of the boy who cried wolf. lol
– mhodges
Nov 19 '18 at 16:50

add a comment |

You cannot reassign const. There's a reason it's named as const, short form for constant. It means, once you define it, it cannot be reassigned.

Variable that has to and needs to be reassigned should be declared as let.

let a = 'a';

a = 'new value'; // this is allowed



const x = 'x';

x = 'new value'; // this is not allowed

var will also let you reassign a value, but it's an old notation and you'll mostly won't need to use var unless for rare specific cases.

In the code from the question

const { count } = this.state;

the count value is destructured from state and assigned to a variable named count, meaning it is a copy of the value this.state.count and not this.state.count itself.

edited Nov 19 '18 at 16:56

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

1

Not sure why someone downvoted this answer 🤔
– Sung Kim
Nov 19 '18 at 16:33

1

I was wondering the same 🧐
– Dinesh Pandiyan
Nov 19 '18 at 16:35

I agree with you, but when you see the given codepen link in the question, it is const
– Yash Karanke
Nov 19 '18 at 16:39

1

Not the downvoter, but "overridden" is an ambiguous term. The value absolutely can be overridden. const means the variable cannot be reassigned
– mhodges
Nov 19 '18 at 16:43

2

While this answer is factually correct, I'm not sure that it answers the OP's question. I think they are asking why, if they declare count as a const (via deconstruction), can that count property on the state object be overwritten. The answer would be that the count variable is a copy of the value, not a reference to the property itself. So declaring it const is only declaring it for that variable, the object property is untouched.
– mhodges
Nov 19 '18 at 16:47

|
show 3 more comments

When you do const { count } = this.state;, you are actually creating a copy of this.state.count, not manipulating this.state.count directly.

And const is there as not to accidentally manipulate it unless you need to.

Following code snippet demos that updating "copy" of count doesn't update the state.count

(click on Run Code Snippet to see the result).

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

And this will fail (miserably).

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

edited Nov 19 '18 at 16:55

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

So you can manipulate a copy given if it is const?
– Yash Karanke
Nov 19 '18 at 16:54

1

@YashKaranke no you can't, if you had declared it as const. I used let to make it modifiable for demo purpose only. If you had const {count} = state; and do count += 999, the snippet will fail. (updated the answer)
– Sung Kim
Nov 19 '18 at 16:55

add a comment |

-1

You can't override const another meaning is you can't reassign const.

const a = 1;

a = 2; // you will get TypeError.  *** numbers and strings are also immutable

but you can modify the constant without reassigning the type

const b = {};

b.a = 'new property'; // { a: "new property" }



const c = ;

c[0] = "new stack"; // ["new stack"]

You can modify but you can't reassign const.

answered Nov 19 '18 at 16:46

Tan

916

add a comment |

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4 Answers
4

active

oldest

votes

4 Answers
4

active

oldest

votes

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

Point taken, but why use const, doesn't it a bit of bad practice given that you know you have to change the state?
– Yash Karanke
Nov 19 '18 at 16:48

1

@YashKaranke Yup, horrible example of using const. There are entire camps of people who believe "use const for everything unless the variable has to be reassigned", which leads to ambiguity and also does not tell the reader what is actually important to not be reassigned vs. what just happens to not be reassigned, but won't hurt anything if it is. It dilutes the meaning of const, kinda like the story of the boy who cried wolf. lol
– mhodges
Nov 19 '18 at 16:50

add a comment |

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

Point taken, but why use const, doesn't it a bit of bad practice given that you know you have to change the state?
– Yash Karanke
Nov 19 '18 at 16:48

1

@YashKaranke Yup, horrible example of using const. There are entire camps of people who believe "use const for everything unless the variable has to be reassigned", which leads to ambiguity and also does not tell the reader what is actually important to not be reassigned vs. what just happens to not be reassigned, but won't hurt anything if it is. It dilutes the meaning of const, kinda like the story of the boy who cried wolf. lol
– mhodges
Nov 19 '18 at 16:50

add a comment |

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

answered Nov 19 '18 at 16:44

Ryan Cogswell

1,560211

Point taken, but why use const, doesn't it a bit of bad practice given that you know you have to change the state?
– Yash Karanke
Nov 19 '18 at 16:48

1

@YashKaranke Yup, horrible example of using const. There are entire camps of people who believe "use const for everything unless the variable has to be reassigned", which leads to ambiguity and also does not tell the reader what is actually important to not be reassigned vs. what just happens to not be reassigned, but won't hurt anything if it is. It dilutes the meaning of const, kinda like the story of the boy who cried wolf. lol
– mhodges
Nov 19 '18 at 16:50

add a comment |

Point taken, but why use const, doesn't it a bit of bad practice given that you know you have to change the state?
– Yash Karanke
Nov 19 '18 at 16:48

1

@YashKaranke Yup, horrible example of using const. There are entire camps of people who believe "use const for everything unless the variable has to be reassigned", which leads to ambiguity and also does not tell the reader what is actually important to not be reassigned vs. what just happens to not be reassigned, but won't hurt anything if it is. It dilutes the meaning of const, kinda like the story of the boy who cried wolf. lol
– mhodges
Nov 19 '18 at 16:50

Point taken, but why use const, doesn't it a bit of bad practice given that you know you have to change the state?
– Yash Karanke
Nov 19 '18 at 16:48

@YashKaranke Yup, horrible example of using const. There are entire camps of people who believe "use const for everything unless the variable has to be reassigned", which leads to ambiguity and also does not tell the reader what is actually important to not be reassigned vs. what just happens to not be reassigned, but won't hurt anything if it is. It dilutes the meaning of const, kinda like the story of the boy who cried wolf. lol
– mhodges
Nov 19 '18 at 16:50

add a comment |

You cannot reassign const. There's a reason it's named as const, short form for constant. It means, once you define it, it cannot be reassigned.

Variable that has to and needs to be reassigned should be declared as let.

let a = 'a';

a = 'new value'; // this is allowed



const x = 'x';

x = 'new value'; // this is not allowed

var will also let you reassign a value, but it's an old notation and you'll mostly won't need to use var unless for rare specific cases.

In the code from the question

const { count } = this.state;

the count value is destructured from state and assigned to a variable named count, meaning it is a copy of the value this.state.count and not this.state.count itself.

edited Nov 19 '18 at 16:56

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

1

Not sure why someone downvoted this answer 🤔
– Sung Kim
Nov 19 '18 at 16:33

1

I was wondering the same 🧐
– Dinesh Pandiyan
Nov 19 '18 at 16:35

I agree with you, but when you see the given codepen link in the question, it is const
– Yash Karanke
Nov 19 '18 at 16:39

1

Not the downvoter, but "overridden" is an ambiguous term. The value absolutely can be overridden. const means the variable cannot be reassigned
– mhodges
Nov 19 '18 at 16:43

2

While this answer is factually correct, I'm not sure that it answers the OP's question. I think they are asking why, if they declare count as a const (via deconstruction), can that count property on the state object be overwritten. The answer would be that the count variable is a copy of the value, not a reference to the property itself. So declaring it const is only declaring it for that variable, the object property is untouched.
– mhodges
Nov 19 '18 at 16:47

|
show 3 more comments

You cannot reassign const. There's a reason it's named as const, short form for constant. It means, once you define it, it cannot be reassigned.

Variable that has to and needs to be reassigned should be declared as let.

let a = 'a';

a = 'new value'; // this is allowed



const x = 'x';

x = 'new value'; // this is not allowed

var will also let you reassign a value, but it's an old notation and you'll mostly won't need to use var unless for rare specific cases.

In the code from the question

const { count } = this.state;

the count value is destructured from state and assigned to a variable named count, meaning it is a copy of the value this.state.count and not this.state.count itself.

edited Nov 19 '18 at 16:56

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

1

Not sure why someone downvoted this answer 🤔
– Sung Kim
Nov 19 '18 at 16:33

1

I was wondering the same 🧐
– Dinesh Pandiyan
Nov 19 '18 at 16:35

I agree with you, but when you see the given codepen link in the question, it is const
– Yash Karanke
Nov 19 '18 at 16:39

1

Not the downvoter, but "overridden" is an ambiguous term. The value absolutely can be overridden. const means the variable cannot be reassigned
– mhodges
Nov 19 '18 at 16:43

2

While this answer is factually correct, I'm not sure that it answers the OP's question. I think they are asking why, if they declare count as a const (via deconstruction), can that count property on the state object be overwritten. The answer would be that the count variable is a copy of the value, not a reference to the property itself. So declaring it const is only declaring it for that variable, the object property is untouched.
– mhodges
Nov 19 '18 at 16:47

|
show 3 more comments

You cannot reassign const. There's a reason it's named as const, short form for constant. It means, once you define it, it cannot be reassigned.

Variable that has to and needs to be reassigned should be declared as let.

let a = 'a';

a = 'new value'; // this is allowed



const x = 'x';

x = 'new value'; // this is not allowed

var will also let you reassign a value, but it's an old notation and you'll mostly won't need to use var unless for rare specific cases.

In the code from the question

const { count } = this.state;

the count value is destructured from state and assigned to a variable named count, meaning it is a copy of the value this.state.count and not this.state.count itself.

edited Nov 19 '18 at 16:56

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

You cannot reassign const. There's a reason it's named as const, short form for constant. It means, once you define it, it cannot be reassigned.

Variable that has to and needs to be reassigned should be declared as let.

let a = 'a';

a = 'new value'; // this is allowed



const x = 'x';

x = 'new value'; // this is not allowed

var will also let you reassign a value, but it's an old notation and you'll mostly won't need to use var unless for rare specific cases.

In the code from the question

const { count } = this.state;

the count value is destructured from state and assigned to a variable named count, meaning it is a copy of the value this.state.count and not this.state.count itself.

edited Nov 19 '18 at 16:56

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

edited Nov 19 '18 at 16:56

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

answered Nov 19 '18 at 16:31

Dinesh Pandiyan

2,465825

1

Not sure why someone downvoted this answer 🤔
– Sung Kim
Nov 19 '18 at 16:33

1

I was wondering the same 🧐
– Dinesh Pandiyan
Nov 19 '18 at 16:35

I agree with you, but when you see the given codepen link in the question, it is const
– Yash Karanke
Nov 19 '18 at 16:39

1

Not the downvoter, but "overridden" is an ambiguous term. The value absolutely can be overridden. const means the variable cannot be reassigned
– mhodges
Nov 19 '18 at 16:43

2

While this answer is factually correct, I'm not sure that it answers the OP's question. I think they are asking why, if they declare count as a const (via deconstruction), can that count property on the state object be overwritten. The answer would be that the count variable is a copy of the value, not a reference to the property itself. So declaring it const is only declaring it for that variable, the object property is untouched.
– mhodges
Nov 19 '18 at 16:47

|
show 3 more comments

1

Not sure why someone downvoted this answer 🤔
– Sung Kim
Nov 19 '18 at 16:33

1

I was wondering the same 🧐
– Dinesh Pandiyan
Nov 19 '18 at 16:35

I agree with you, but when you see the given codepen link in the question, it is const
– Yash Karanke
Nov 19 '18 at 16:39

1

Not the downvoter, but "overridden" is an ambiguous term. The value absolutely can be overridden. const means the variable cannot be reassigned
– mhodges
Nov 19 '18 at 16:43

2

While this answer is factually correct, I'm not sure that it answers the OP's question. I think they are asking why, if they declare count as a const (via deconstruction), can that count property on the state object be overwritten. The answer would be that the count variable is a copy of the value, not a reference to the property itself. So declaring it const is only declaring it for that variable, the object property is untouched.
– mhodges
Nov 19 '18 at 16:47

Not sure why someone downvoted this answer 🤔
– Sung Kim
Nov 19 '18 at 16:33

I was wondering the same 🧐
– Dinesh Pandiyan
Nov 19 '18 at 16:35

I agree with you, but when you see the given codepen link in the question, it is const
– Yash Karanke
Nov 19 '18 at 16:39

Not the downvoter, but "overridden" is an ambiguous term. The value absolutely can be overridden. const means the variable cannot be reassigned
– mhodges
Nov 19 '18 at 16:43

While this answer is factually correct, I'm not sure that it answers the OP's question. I think they are asking why, if they declare count as a const (via deconstruction), can that count property on the state object be overwritten. The answer would be that the count variable is a copy of the value, not a reference to the property itself. So declaring it const is only declaring it for that variable, the object property is untouched.
– mhodges
Nov 19 '18 at 16:47

|
show 3 more comments

When you do const { count } = this.state;, you are actually creating a copy of this.state.count, not manipulating this.state.count directly.

And const is there as not to accidentally manipulate it unless you need to.

Following code snippet demos that updating "copy" of count doesn't update the state.count

(click on Run Code Snippet to see the result).

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

And this will fail (miserably).

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

edited Nov 19 '18 at 16:55

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

So you can manipulate a copy given if it is const?
– Yash Karanke
Nov 19 '18 at 16:54

1

@YashKaranke no you can't, if you had declared it as const. I used let to make it modifiable for demo purpose only. If you had const {count} = state; and do count += 999, the snippet will fail. (updated the answer)
– Sung Kim
Nov 19 '18 at 16:55

add a comment |

When you do const { count } = this.state;, you are actually creating a copy of this.state.count, not manipulating this.state.count directly.

And const is there as not to accidentally manipulate it unless you need to.

Following code snippet demos that updating "copy" of count doesn't update the state.count

(click on Run Code Snippet to see the result).

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

And this will fail (miserably).

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

edited Nov 19 '18 at 16:55

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

So you can manipulate a copy given if it is const?
– Yash Karanke
Nov 19 '18 at 16:54

1

@YashKaranke no you can't, if you had declared it as const. I used let to make it modifiable for demo purpose only. If you had const {count} = state; and do count += 999, the snippet will fail. (updated the answer)
– Sung Kim
Nov 19 '18 at 16:55

add a comment |

When you do const { count } = this.state;, you are actually creating a copy of this.state.count, not manipulating this.state.count directly.

And const is there as not to accidentally manipulate it unless you need to.

Following code snippet demos that updating "copy" of count doesn't update the state.count

(click on Run Code Snippet to see the result).

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

And this will fail (miserably).

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

edited Nov 19 '18 at 16:55

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

When you do const { count } = this.state;, you are actually creating a copy of this.state.count, not manipulating this.state.count directly.

And const is there as not to accidentally manipulate it unless you need to.

Following code snippet demos that updating "copy" of count doesn't update the state.count

(click on Run Code Snippet to see the result).

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

And this will fail (miserably).

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

const state = { count: 0 };

let {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

const state = { count: 0 };

const {count} = state;

count += 999;



console.log(`state.count`, state.count);

console.log(`count`, count);

edited Nov 19 '18 at 16:55

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

edited Nov 19 '18 at 16:55

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

answered Nov 19 '18 at 16:51

Sung Kim

17.4k33111161

So you can manipulate a copy given if it is const?
– Yash Karanke
Nov 19 '18 at 16:54

1

@YashKaranke no you can't, if you had declared it as const. I used let to make it modifiable for demo purpose only. If you had const {count} = state; and do count += 999, the snippet will fail. (updated the answer)
– Sung Kim
Nov 19 '18 at 16:55

add a comment |

So you can manipulate a copy given if it is const?
– Yash Karanke
Nov 19 '18 at 16:54

1

@YashKaranke no you can't, if you had declared it as const. I used let to make it modifiable for demo purpose only. If you had const {count} = state; and do count += 999, the snippet will fail. (updated the answer)
– Sung Kim
Nov 19 '18 at 16:55

So you can manipulate a copy given if it is const?
– Yash Karanke
Nov 19 '18 at 16:54

@YashKaranke no you can't, if you had declared it as const. I used let to make it modifiable for demo purpose only. If you had const {count} = state; and do count += 999, the snippet will fail. (updated the answer)
– Sung Kim
Nov 19 '18 at 16:55

add a comment |

-1

You can't override const another meaning is you can't reassign const.

const a = 1;

a = 2; // you will get TypeError.  *** numbers and strings are also immutable

but you can modify the constant without reassigning the type

const b = {};

b.a = 'new property'; // { a: "new property" }



const c = ;

c[0] = "new stack"; // ["new stack"]

You can modify but you can't reassign const.

answered Nov 19 '18 at 16:46

Tan

916

add a comment |

-1

You can't override const another meaning is you can't reassign const.

const a = 1;

a = 2; // you will get TypeError.  *** numbers and strings are also immutable

but you can modify the constant without reassigning the type

const b = {};

b.a = 'new property'; // { a: "new property" }



const c = ;

c[0] = "new stack"; // ["new stack"]

You can modify but you can't reassign const.

answered Nov 19 '18 at 16:46

Tan

916

add a comment |

-1

You can't override const another meaning is you can't reassign const.

const a = 1;

a = 2; // you will get TypeError.  *** numbers and strings are also immutable

but you can modify the constant without reassigning the type

const b = {};

b.a = 'new property'; // { a: "new property" }



const c = ;

c[0] = "new stack"; // ["new stack"]

You can modify but you can't reassign const.

answered Nov 19 '18 at 16:46

Tan

916

You can't override const another meaning is you can't reassign const.

const a = 1;

a = 2; // you will get TypeError.  *** numbers and strings are also immutable

but you can modify the constant without reassigning the type

const b = {};

b.a = 'new property'; // { a: "new property" }



const c = ;

c[0] = "new stack"; // ["new stack"]

You can modify but you can't reassign const.

answered Nov 19 '18 at 16:46

Tan

916

answered Nov 19 '18 at 16:46

Tan

916

answered Nov 19 '18 at 16:46

Tan

916

answered Nov 19 '18 at 16:46

Tan

916

add a comment |

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