124 lines
2.6 KiB
Markdown
124 lines
2.6 KiB
Markdown
# babel-plugin-syntax-trailing-function-commas
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Compile trailing function commas to ES5
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```js
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function clownPuppiesEverywhere(
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param1,
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param2,
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) { /* ... */ }
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clownPuppiesEverywhere(
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'foo',
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'bar',
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);
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```
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[Try in REPL](http://babeljs.io/repl/#?evaluate=true&presets=es2015%2Cstage-0&code=function%20clownPuppiesEverywhere(%0A%20%20param1%2C%0A%20%20param2%2C%0A)%20%7B%20%2F*%20...%20*%2F%20%7D%0A%0AclownPuppiesEverywhere(%0A%20%20'foo'%2C%0A%20%20'bar'%2C%0A)%3B)
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## Example
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### Basic
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This is an example from the [Proposal](https://github.com/jeffmo/es-trailing-function-commas).
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Let's say you have this function:
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```js
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function clownPuppiesEverywhere(
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param1,
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param2
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) { /* ... */ }
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clownPuppiesEverywhere(
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'foo',
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'bar'
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);
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```
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If you want to have a new parameter called `param3`, the diff output would be like that:
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```diff
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function clownPuppiesEverywhere(
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param1,
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- param2
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+ param2, // Change this line to add a comma
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+ param3 // Add param3
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) { /* ... */ }
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clownPuppiesEverywhere(
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'foo',
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- 'bar'
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+ 'bar', // Change this line to add a comma
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+ 'baz' // Add param3
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);
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```
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In total, you have to change 2 lines for the function declaration and 2 lines for each usage.
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If you had your function defined with trailing commas:
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```js
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function clownPuppiesEverywhere(
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param1,
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param2,
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) { /* ... */ }
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clownPuppiesEverywhere(
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'foo',
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'bar',
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);
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```
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Adding a new parameter would only change one line in the function declaration and one line for each usage:
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```diff
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function clownPuppiesEverywhere(
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param1,
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param2,
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+ param3, // Add param3
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) { /* ... */ }
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clownPuppiesEverywhere(
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'foo',
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'bar',
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+ 'baz', // Add param3
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);
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```
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In the end, your diff output will be cleaner and easier to read, it would be much quicker to add a new parameter to your functions, it also makes it easier to copy paste elements and move code around.
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## Installation
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```sh
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npm install --save-dev babel-plugin-syntax-trailing-function-commas
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```
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## Usage
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### Via `.babelrc` (Recommended)
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**.babelrc**
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```json
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{
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"plugins": ["syntax-trailing-function-commas"]
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}
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```
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### Via CLI
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```sh
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babel --plugins syntax-trailing-function-commas script.js
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```
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### Via Node API
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```javascript
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require("babel-core").transform("code", {
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plugins: ["syntax-trailing-function-commas"]
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});
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```
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## References
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* [Proposal](https://github.com/jeffmo/es-trailing-function-commas)
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* [Spec](http://jeffmo.github.io/es-trailing-function-commas/)
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* [Why you should enforce Dangling Commas for Multiline Statements](https://medium.com/@nikgraf/why-you-should-enforce-dangling-commas-for-multiline-statements-d034c98e36f8)
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