Extract code blocks by language

Goal: Pull out only the code blocks written in a specific language, e.g. to review all the JavaScript snippets in a doc.

Prerequisites: None.

Query

select(.code.lang == "js")

$ mq 'select(.code.lang == "js")' README.md

Input

```js
const x = 1;
```

```python
x = 1
```

```js
const y = 2;
```

Output

Returns only the two JavaScript code blocks (const x = 1; and const y = 2;), dropping the Python one.

Notes

• Shorthand: .code("js") selects the same nodes as select(.code.lang == "js"). The language selector doubles as a filter when called with an argument.
• To see which languages appear in a document at all, use .code.lang on its own. It prints one language per code block, in document order, with duplicates (js, python, js, …), not a deduplicated list. Pipe through -A ... | unique_by(fn(x): x;) if you need the distinct set.
• To strip code blocks out and keep only prose, invert the condition: select(!.code).