Difference between export default myVar and export default myFunc()

Is there any perf difference between:

const myVar = myFunc()

export default myVar

and:

export default myFunc()

I prefer the 2nd notation (more concise, less code), but I don't know if it has an impact on performance. Each code loading this module will point to the same reference, or to a new one ?

asked Nov 13 '18 at 12:13

soywod

1,5711819

It's the same myFunc() will only be called once.

– Keith
Nov 13 '18 at 12:15

1

"Each code loading this module will point to the same reference, or to a new one ?" Modules are always only evaluated once (the first time they are loaded).

– Felix Kling
Nov 13 '18 at 17:23

add a comment |

Is there any perf difference between:

const myVar = myFunc()

export default myVar

and:

export default myFunc()

I prefer the 2nd notation (more concise, less code), but I don't know if it has an impact on performance. Each code loading this module will point to the same reference, or to a new one ?

asked Nov 13 '18 at 12:13

soywod

1,5711819

It's the same myFunc() will only be called once.

– Keith
Nov 13 '18 at 12:15

1

"Each code loading this module will point to the same reference, or to a new one ?" Modules are always only evaluated once (the first time they are loaded).

– Felix Kling
Nov 13 '18 at 17:23

add a comment |

Is there any perf difference between:

const myVar = myFunc()

export default myVar

and:

export default myFunc()

I prefer the 2nd notation (more concise, less code), but I don't know if it has an impact on performance. Each code loading this module will point to the same reference, or to a new one ?

asked Nov 13 '18 at 12:13

soywod

1,5711819

Is there any perf difference between:

const myVar = myFunc()

export default myVar

and:

export default myFunc()

I prefer the 2nd notation (more concise, less code), but I don't know if it has an impact on performance. Each code loading this module will point to the same reference, or to a new one ?

javascript ecmascript-6 export

asked Nov 13 '18 at 12:13

soywod

1,5711819

asked Nov 13 '18 at 12:13

soywod

1,5711819

asked Nov 13 '18 at 12:13

soywod

1,5711819

asked Nov 13 '18 at 12:13

soywod

1,5711819

asked Nov 13 '18 at 12:13

soywod

1,5711819

It's the same myFunc() will only be called once.

– Keith
Nov 13 '18 at 12:15

1

"Each code loading this module will point to the same reference, or to a new one ?" Modules are always only evaluated once (the first time they are loaded).

– Felix Kling
Nov 13 '18 at 17:23

add a comment |

It's the same myFunc() will only be called once.

– Keith
Nov 13 '18 at 12:15

1

"Each code loading this module will point to the same reference, or to a new one ?" Modules are always only evaluated once (the first time they are loaded).

– Felix Kling
Nov 13 '18 at 17:23

It's the same myFunc() will only be called once.

– Keith
Nov 13 '18 at 12:15

"Each code loading this module will point to the same reference, or to a new one ?" Modules are always only evaluated once (the first time they are loaded).

– Felix Kling
Nov 13 '18 at 17:23

add a comment |

2 Answers
2

active

oldest

votes

There is no difference in this case.

You simply use an alias.

So the reference will be the same each time.

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

Okey, and is the 2nd considered as a bad practice ? I don't see this often, but I like the idea. Even with export default function() { ... }, but seems not so common.

– soywod
Nov 14 '18 at 8:28

@soywod The most common (and good, my opinion) practice is to export 1 object from a file, which contents a list of props. So you will have a singleton interface for a file. And all your imports will have the same structure. And they are expandable better. As for exporting only 1 thing for a file it's no a big sence if you use 1st or 2nd, but the better option will be an object with 1 field (for same import/export structure)

– Eugene Mihaylin
Nov 14 '18 at 9:07

I see it a bit differently. The fact to use default export force yourself to apply the Single Responsibility pattern. I have never more than one export to do by file (except for types in fact, so I use import myFunc, {MyType} from ...). That why I often use the default, and that's why I came to this export default function() { ... }.

– soywod
Nov 14 '18 at 10:26

add a comment |

You can find really good explanations here:
https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export#Using_the_default_export
and
What is "export default" in javascript?

answered Nov 13 '18 at 13:37

squeekyDave

373114

2

Link only answers are considered poor quality. It also doesn't seem to address the question.

– Felix Kling
Nov 13 '18 at 17:21

I know how import / export works, this is not answering my question.

– soywod
Nov 14 '18 at 8:27

@soywod Apologies then, note taken.

– squeekyDave
Nov 14 '18 at 9:23

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

There is no difference in this case.

You simply use an alias.

So the reference will be the same each time.

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

Okey, and is the 2nd considered as a bad practice ? I don't see this often, but I like the idea. Even with export default function() { ... }, but seems not so common.

– soywod
Nov 14 '18 at 8:28

@soywod The most common (and good, my opinion) practice is to export 1 object from a file, which contents a list of props. So you will have a singleton interface for a file. And all your imports will have the same structure. And they are expandable better. As for exporting only 1 thing for a file it's no a big sence if you use 1st or 2nd, but the better option will be an object with 1 field (for same import/export structure)

– Eugene Mihaylin
Nov 14 '18 at 9:07

I see it a bit differently. The fact to use default export force yourself to apply the Single Responsibility pattern. I have never more than one export to do by file (except for types in fact, so I use import myFunc, {MyType} from ...). That why I often use the default, and that's why I came to this export default function() { ... }.

– soywod
Nov 14 '18 at 10:26

add a comment |

There is no difference in this case.

You simply use an alias.

So the reference will be the same each time.

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

Okey, and is the 2nd considered as a bad practice ? I don't see this often, but I like the idea. Even with export default function() { ... }, but seems not so common.

– soywod
Nov 14 '18 at 8:28

@soywod The most common (and good, my opinion) practice is to export 1 object from a file, which contents a list of props. So you will have a singleton interface for a file. And all your imports will have the same structure. And they are expandable better. As for exporting only 1 thing for a file it's no a big sence if you use 1st or 2nd, but the better option will be an object with 1 field (for same import/export structure)

– Eugene Mihaylin
Nov 14 '18 at 9:07

I see it a bit differently. The fact to use default export force yourself to apply the Single Responsibility pattern. I have never more than one export to do by file (except for types in fact, so I use import myFunc, {MyType} from ...). That why I often use the default, and that's why I came to this export default function() { ... }.

– soywod
Nov 14 '18 at 10:26

add a comment |

There is no difference in this case.

You simply use an alias.

So the reference will be the same each time.

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

There is no difference in this case.

You simply use an alias.

So the reference will be the same each time.

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

answered Nov 13 '18 at 12:17

Eugene Mihaylin

9581424

Okey, and is the 2nd considered as a bad practice ? I don't see this often, but I like the idea. Even with export default function() { ... }, but seems not so common.

– soywod
Nov 14 '18 at 8:28

@soywod The most common (and good, my opinion) practice is to export 1 object from a file, which contents a list of props. So you will have a singleton interface for a file. And all your imports will have the same structure. And they are expandable better. As for exporting only 1 thing for a file it's no a big sence if you use 1st or 2nd, but the better option will be an object with 1 field (for same import/export structure)

– Eugene Mihaylin
Nov 14 '18 at 9:07

I see it a bit differently. The fact to use default export force yourself to apply the Single Responsibility pattern. I have never more than one export to do by file (except for types in fact, so I use import myFunc, {MyType} from ...). That why I often use the default, and that's why I came to this export default function() { ... }.

– soywod
Nov 14 '18 at 10:26

add a comment |

Okey, and is the 2nd considered as a bad practice ? I don't see this often, but I like the idea. Even with export default function() { ... }, but seems not so common.

– soywod
Nov 14 '18 at 8:28

@soywod The most common (and good, my opinion) practice is to export 1 object from a file, which contents a list of props. So you will have a singleton interface for a file. And all your imports will have the same structure. And they are expandable better. As for exporting only 1 thing for a file it's no a big sence if you use 1st or 2nd, but the better option will be an object with 1 field (for same import/export structure)

– Eugene Mihaylin
Nov 14 '18 at 9:07

I see it a bit differently. The fact to use default export force yourself to apply the Single Responsibility pattern. I have never more than one export to do by file (except for types in fact, so I use import myFunc, {MyType} from ...). That why I often use the default, and that's why I came to this export default function() { ... }.

– soywod
Nov 14 '18 at 10:26

Okey, and is the 2nd considered as a bad practice ? I don't see this often, but I like the idea. Even with export default function() { ... }, but seems not so common.

– soywod
Nov 14 '18 at 8:28

@soywod The most common (and good, my opinion) practice is to export 1 object from a file, which contents a list of props. So you will have a singleton interface for a file. And all your imports will have the same structure. And they are expandable better. As for exporting only 1 thing for a file it's no a big sence if you use 1st or 2nd, but the better option will be an object with 1 field (for same import/export structure)

– Eugene Mihaylin
Nov 14 '18 at 9:07

I see it a bit differently. The fact to use default export force yourself to apply the Single Responsibility pattern. I have never more than one export to do by file (except for types in fact, so I use import myFunc, {MyType} from ...). That why I often use the default, and that's why I came to this export default function() { ... }.

– soywod
Nov 14 '18 at 10:26

add a comment |

You can find really good explanations here:
https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export#Using_the_default_export
and
What is "export default" in javascript?

answered Nov 13 '18 at 13:37

squeekyDave

373114

2

Link only answers are considered poor quality. It also doesn't seem to address the question.

– Felix Kling
Nov 13 '18 at 17:21

I know how import / export works, this is not answering my question.

– soywod
Nov 14 '18 at 8:27

@soywod Apologies then, note taken.

– squeekyDave
Nov 14 '18 at 9:23

add a comment |

You can find really good explanations here:
https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export#Using_the_default_export
and
What is "export default" in javascript?

answered Nov 13 '18 at 13:37

squeekyDave

373114

2

Link only answers are considered poor quality. It also doesn't seem to address the question.

– Felix Kling
Nov 13 '18 at 17:21

I know how import / export works, this is not answering my question.

– soywod
Nov 14 '18 at 8:27

@soywod Apologies then, note taken.

– squeekyDave
Nov 14 '18 at 9:23

add a comment |

You can find really good explanations here:
https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export#Using_the_default_export
and
What is "export default" in javascript?

answered Nov 13 '18 at 13:37

squeekyDave

373114

You can find really good explanations here:
https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export#Using_the_default_export
and
What is "export default" in javascript?

answered Nov 13 '18 at 13:37

squeekyDave

373114

answered Nov 13 '18 at 13:37

squeekyDave

373114

answered Nov 13 '18 at 13:37

squeekyDave

373114

answered Nov 13 '18 at 13:37

squeekyDave

373114

2

Link only answers are considered poor quality. It also doesn't seem to address the question.

– Felix Kling
Nov 13 '18 at 17:21

I know how import / export works, this is not answering my question.

– soywod
Nov 14 '18 at 8:27

@soywod Apologies then, note taken.

– squeekyDave
Nov 14 '18 at 9:23

add a comment |

2

Link only answers are considered poor quality. It also doesn't seem to address the question.

– Felix Kling
Nov 13 '18 at 17:21

I know how import / export works, this is not answering my question.

– soywod
Nov 14 '18 at 8:27

@soywod Apologies then, note taken.

– squeekyDave
Nov 14 '18 at 9:23

Link only answers are considered poor quality. It also doesn't seem to address the question.

– Felix Kling
Nov 13 '18 at 17:21

I know how import / export works, this is not answering my question.

– soywod
Nov 14 '18 at 8:27

@soywod Apologies then, note taken.

– squeekyDave
Nov 14 '18 at 9:23

add a comment |

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