Code

Code blocks can be used to display multiple lines of code. They preserve formatting and provide syntax highlighting when possible.

Start and end a code block with a code fence. A code fence is a sequence of at least three consecutive backtick characters ```. You can optionally add a language identifier to enable syntax highlighting.

project:
  title: MyST Markdown
  github: https://github.com/jupyter-book/mystmd

```yaml
project:
  title: MyST Markdown
  github: https://github.com/jupyter-book/mystmd
```

There are two ways to add callouts to a code block. When using callouts, you must use one callout format. You cannot combine explicit and magic callouts.

Add <\d+> to the end of a line to explicitly create a code callout.

An ordered list with the same number of items as callouts must follow the code block. If the number of list items doesn’t match the callouts, docs-builder will throw an error.

project:
  license:
    content: CC-BY-4.0 1

```yaml
project:
  license:
    content: CC-BY-4.0 <1>
```

1. The license

You can also have one block element in between the code block and the callout list:

var input1 = "World";1
var input2 = "Elastic";2

function render(input) {
    return `Hello, ${input}!`;
}

render(input1);
render(input2);

```javascript
var input1 = "World"; // <1>
var input2 = "Elastic"; // <2>

function render(input) {
    return `Hello, ${input}!`;
}

render(input1);
render(input2);
```

**Inputs:**

1. `World`
2. `Elastic`

**Outputs**:

1. `Hello, World!`
2. `Hello, Elastic!`

If a code block contains code comments in the form of // or #, callouts will be magically created 🪄.

var apiKey = new ApiKey("<API_KEY>");1
var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);

```csharp
var apiKey = new ApiKey("<API_KEY>"); // Set up the api key
var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);
```

Code comments must follow code to be hoisted as a callout. For example:

// THIS IS NOT A CALLOUT
var apiKey = new ApiKey("<API_KEY>");1
var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);

```csharp
// THIS IS NOT A CALLOUT
var apiKey = new ApiKey("<API_KEY>"); // This is a callout
var client = new ElasticsearchClient("<CLOUD_ID>", apiKey);
```

We document a lot of API endpoints at Elastic. For these endpoints, we support console as a language. The term console relates to the dev console in kibana which users can link to directly from these code snippets.

In a console code block, the first line is highlighted as a dev console string and the remainder as json:

 GET /mydocuments/_search {
    "from": 1,
    "query": {
        "match_all" {}
    }
}

```console
GET /mydocuments/_search
{
    "from": 1,
    "query": {
        "match_all" {}
    }
}
```

Use backticks to create an inline code span.
Inline code spans are useful for short code snippets or variable names.

This `code` is inline.

## This `code` is in a heading.