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- # babel-plugin-syntax-trailing-function-commas
- Compile trailing function commas to ES5
- ```js
- function clownPuppiesEverywhere(
- param1,
- param2,
- ) { /* ... */ }
- clownPuppiesEverywhere(
- 'foo',
- 'bar',
- );
- ```
- [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)
- ## Example
- ### Basic
- This is an example from the [Proposal](https://github.com/jeffmo/es-trailing-function-commas).
- Let's say you have this function:
- ```js
- function clownPuppiesEverywhere(
- param1,
- param2
- ) { /* ... */ }
- clownPuppiesEverywhere(
- 'foo',
- 'bar'
- );
- ```
- If you want to have a new parameter called `param3`, the diff output would be like that:
- ```diff
- function clownPuppiesEverywhere(
- param1,
- - param2
- + param2, // Change this line to add a comma
- + param3 // Add param3
- ) { /* ... */ }
- clownPuppiesEverywhere(
- 'foo',
- - 'bar'
- + 'bar', // Change this line to add a comma
- + 'baz' // Add param3
- );
- ```
- In total, you have to change 2 lines for the function declaration and 2 lines for each usage.
- If you had your function defined with trailing commas:
- ```js
- function clownPuppiesEverywhere(
- param1,
- param2,
- ) { /* ... */ }
- clownPuppiesEverywhere(
- 'foo',
- 'bar',
- );
- ```
- Adding a new parameter would only change one line in the function declaration and one line for each usage:
- ```diff
- function clownPuppiesEverywhere(
- param1,
- param2,
- + param3, // Add param3
- ) { /* ... */ }
- clownPuppiesEverywhere(
- 'foo',
- 'bar',
- + 'baz', // Add param3
- );
- ```
- 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.
- ## Installation
- ```sh
- npm install --save-dev babel-plugin-syntax-trailing-function-commas
- ```
- ## Usage
- ### Via `.babelrc` (Recommended)
- **.babelrc**
- ```json
- {
- "plugins": ["syntax-trailing-function-commas"]
- }
- ```
- ### Via CLI
- ```sh
- babel --plugins syntax-trailing-function-commas script.js
- ```
- ### Via Node API
- ```javascript
- require("babel-core").transform("code", {
- plugins: ["syntax-trailing-function-commas"]
- });
- ```
- ## References
- * [Proposal](https://github.com/jeffmo/es-trailing-function-commas)
- * [Spec](http://jeffmo.github.io/es-trailing-function-commas/)
- * [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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