> For the complete documentation index, see [llms.txt](https://zurassic.gitbook.io/10x-developer/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://zurassic.gitbook.io/10x-developer/javascript/coffeescript_to_es6.md).

# CoffeeScript to ES6 cheatsheet

References:

* <https://gist.github.com/danielgtaylor/0b60c2ed1f069f118562>
* <https://robots.thoughtbot.com/replace-coffeescript-with-es6>

## Iteration

* On object properties:

```javascript
// coffee
for prop, value of obj

// ES6
_.each(obj, (value, key)=>{
});

// or (NOTE don't use it for array)
for (let prop in obj) {
}
```

* On collection (array):

```javascript
// coffee
for ele in arr
    console.log ele

// es6
for (let ele of arr) {
    console.log(ele);
}

// or
arr.forEach( (ele) => {
    console.log(ele);
    //  函数体内的this对象，就是定义时所在的对象，而不是使用时所在的对象
});

// or
arr.forEach(function(ele){
    console.log(ele);
    //  this is the function
});
```

## Misc

* Replace `==`/`!=` with `===`/`!==`
* [There is no concept of class variable in ES6](http://stackoverflow.com/questions/22528967/es6-class-variable-alternatives), you might want to just turn that to a static method:

```javascript
// coffee
class MyFile
    @EXT = '.myfile'

// es6
class MyFile {
  static Ext() {
    return '.myfile';
  }
}
```


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