mirror of
https://github.com/jashkenas/coffeescript.git
synced 2026-05-03 03:00:14 -04:00
8061ecf0e2
* Move analytics initialization into docs.coffee * Bump Bootstrap and CodeMirror versions * Update output * Merge CodeMirror styles * Update CodeMirror styles * Better flexbox layout for docs, including flex auto-sized sidebar and main column * Minor styling fixes for Edge * Fix scrollspy for new layout * Update output * Clicking on the CoffeeScript logo in the navbar should scroll to top; fix main column width on mobile * Update output * 2.3.0 changelog * Update operators section for ** * Update docs for ES2018 object rest/spread * Remove references to Node's experimental modules support * Move the README coffee cup to the right side, so our name isn't cut off on the NPM page; update README and CONTRIBUTING text * Update dependencies * Add compatibility note for async generators * Bump version to 2.3.0 and update output * Have CI test in Node 10 instead of 9 * Somehow this gets generated slightly differently in Node 10 * Fix #4042: Update broken link
49 lines
1.8 KiB
Markdown
49 lines
1.8 KiB
Markdown
## Operators and Aliases
|
||
|
||
Because the `==` operator frequently causes undesirable coercion, is intransitive, and has a different meaning than in other languages, CoffeeScript compiles `==` into `===`, and `!=` into `!==`. In addition, `is` compiles into `===`, and `isnt` into `!==`.
|
||
|
||
You can use `not` as an alias for `!`.
|
||
|
||
For logic, `and` compiles to `&&`, and `or` into `||`.
|
||
|
||
Instead of a newline or semicolon, `then` can be used to separate conditions from expressions, in `while`, `if`/`else`, and `switch`/`when` statements.
|
||
|
||
As in [YAML](http://yaml.org/), `on` and `yes` are the same as boolean `true`, while `off` and `no` are boolean `false`.
|
||
|
||
`unless` can be used as the inverse of `if`.
|
||
|
||
As a shortcut for `this.property`, you can use `@property`.
|
||
|
||
You can use `in` to test for array presence, and `of` to test for JavaScript object-key presence.
|
||
|
||
In a `for` loop, `from` compiles to the [ES2015 `of`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of). (Yes, it’s unfortunate; the CoffeeScript `of` predates the ES2015 `of`.)
|
||
|
||
To simplify math expressions, `**` can be used for exponentiation and `//` performs floor division. `%` works just like in JavaScript, while `%%` provides [“dividend dependent modulo”](https://en.wikipedia.org/wiki/Modulo_operation):
|
||
|
||
```
|
||
codeFor('modulo')
|
||
```
|
||
|
||
All together now:
|
||
|
||
| CoffeeScript | JavaScript |
|
||
| --- | --- |
|
||
| `is` | `===` |
|
||
| `isnt` | `!==` |
|
||
| `not` | `!` |
|
||
| `and` | `&&` |
|
||
| `or` | `||` |
|
||
| `true`, `yes`, `on` | `true` |
|
||
| `false`, `no`, `off`  | `false` |
|
||
| `@`, `this` | `this` |
|
||
| `a in b` | `[].indexOf.call(b, a) >= 0` |
|
||
| `a of b` | `a in b` |
|
||
| `for a from b` | `for (a of b)` |
|
||
| `a ** b` | `a ** b` |
|
||
| `a // b` | `Math.floor(a / b)` |
|
||
| `a %% b` | `(a % b + b) % b` |
|
||
|
||
```
|
||
codeFor('aliases')
|
||
```
|