node-jq is a Node.js wrapper for jq - a lightweight and flexible command-line JSON processor
$ npm install node-jq --save
# or
$ yarn add node-jq
You can use jq
directly after installing it:
npx node-jq '.foo' package.json
By default, node-jq
downloads jq
during the installation process with a post-install script. Depending on your SO downloads from [https://github.com/jqlang/jq/releases] into ./node_modules/node-jq/bin/jq
to avoid colisions with any global installation. Check #161 #167 #171 for more information. You can safely rely on this location for your installed jq
, we won't change this path without a major version upgrade.
If you want to skip the installation step of jq
, you can set NODE_JQ_SKIP_INSTALL_BINARY
to true
or ignore the post-install script from the installation npm install node-jq --ignore-scripts
.
export NODE_JQ_SKIP_INSTALL_BINARY=true
npm install node-jq
npm install node-jq --ignore-scripts
Usually in your CLI using jq
:
jq ".abilities[].moves" bulbasaur.json
and you get
{
"name": "heartgold-soulsilver",
"power": "10"
}
{
"name": "platinum",
"power": "50"
}
{
"name": "diamond-pearl",
"power": "99"
}
With node-jq
you could run it programmatically and interact with the output as a JavaScript Object:
NOTE: Take care of the filter that you are using with
jq
, mapping an array or any other iterative output isn't a valid JavaScript Object, that might fail at parse-time.
const jq = require('node-jq')
const filter = '.abilities[].moves'
const jsonPath = '/path/to/bulbasaur.json'
const options = {}
jq.run(filter, jsonPath, options)
.then((output) => {
console.log(output)
/*
{
"name": "heartgold-soulsilver",
"power": "10"
},
{
"name": "platinum",
"power": "50"
},
{
"name": "diamond-pearl",
"power": "99"
}
*/
})
.catch((err) => {
console.error(err)
// Something went wrong...
})
By default, the jq
binary installed with the package is used. If you have special needs or want to use another binary in a different
path you can set the environment variable JQ_PATH
to override the binary path.
Description | Type | Values | Default |
---|---|---|---|
Type of input | string | 'file' , 'json' , 'string' |
'file' |
input: 'file'
Run the jq query against a JSON file.
jq.run('.', '/path/to/file.json').then(console.log)
// { "foo": "bar" }
input: 'file'
with multiple filesRun jq query against multiple JSON files.
jq.run('.', ['/path/to/file.json','path/to/other_file.json']).then(console.log)
// { "foo": "bar" }
// { "otherFoo": "andBar" }
input: 'json'
Run the jq
query against an Object.
jq.run('.', { foo: 'bar' }, { input: 'json' }).then(console.log)
// { "foo": "bar" }
input: 'string'
Run the jq query against a String.
jq.run('.', '{ foo: "bar" }', { input: 'string' }).then(console.log)
// { "foo": "bar" }
Description | Values | Default |
---|---|---|
Type of output | 'pretty' , 'json' , 'compact' , 'string' |
'pretty' |
output: 'pretty'
Return the output as a String.
jq.run('.', '/path/to/file.json', { output: 'string' }).then(console.log)
// {
// "foo": "bar"
// }
output: 'json'
Return the output as an Object.
jq.run('.', '/path/to/file.json', { output: 'json' }).then(console.log)
// { foo: 'bar' }
output: 'compact'|'string'
Return the output as a String.
jq.run('.', '/path/to/file.json', { output: 'compact' }).then(console.log)
// {"foo":"bar"}
jq.run('.', '/path/to/file.json', { output: 'string' }).then(console.log)
// {"foo":"bar"}
Description | Values | Default |
---|---|---|
Read input stream into array | true , false |
false |
slurp: true
Read input stream into array.
jq.run('.', ['/path/to/file.json','/path/to/other_file.json'], { output: 'json', slurp: true }).then(console.log)
// [
// {
// "foo": "bar"
// },
// {
// "otherFoo": "andBar"
// }
// ]
Description | Values | Default |
---|---|---|
Sort object keys in alphabetical order | true , false |
false |
sort: true
Sorts object keys alphabetically.
jq.run('.', ['/path/to/file.json'], { output: 'json', sort: true }).then(console.log)
// {
// "a": 2,
// "b": 1
// },
Description | Values | Default |
---|---|---|
Send custom args to the jq command | [object] |
undefined |
args: { myfruit: { hello: 'orange'}, myfruit2: "banana" }
Adds the --argjson myfruit "{ 'hello': 'orange' }" --arg myfruit2 orange
arguments to the internal jq command
jq.run('{"fruit":$myfruit,"fruit2":$myfruit2}', ['/path/to/file.json'], { output: 'json', sort: true, args: { myfruit: { hello: 'orange' }, myfruit2: "banana" } }).then(console.log)
// {
// fruit: {
// hello: "orange"
// },
// fruit2: "banana"
// }
Description | Values | Default |
---|---|---|
Set working dir for jq process |
valid path | process.cwd() |
jq.run('.', ['file.json'], { output: 'json', sort: true }, '/path/to').then(console.log)
// {
// "a": 2,
// "b": 1
// },
Description | Values | Default |
---|---|---|
Run jq process as detached process |
true , false |
false |
By default jq
process will run 'attached' to the main process. That means that any interrupt signal main process receives will be propagated to jq
process. For example, if main process receives SIGTERM
, jq
will also receive it and exit immediately.
However, in some cases you might not want jq
to exit immediately and let it exit normally. For example, if you want to implement a graceful shutdown - main process receives SIGTERM
, it finishes processing current json file and exits after processing is completed.
To achieve that run jq
detached and NodeJS will not propagate SIGTERM
to jq
process allowing it to run until it completes.
jq.run('.', ['file.json'], { output: 'json', sort: true }, undefined, true).then(console.log)
// {
// "a": 2,
// "b": 1
// },
Why would you want to manipulate JavaScript Objects with jq
inside a nodejs app, when there are tools like ramda or lodash?
The idea was to port jq
in node to be able to run it as-is. node-jq
doesn't try to replace Array
/Object
filters, maps, transformations, and so on.
Our primary goal was to make jq
syntax available inside an Atom extension: atom-jq.
Other than that, jq
is an interesting CLI tool to quickly parse and manipulate the response of an API, such as:
curl 'https://jsonplaceholder.typicode.com/comments' | jq '.[].postId'
There are also people dealing with complex use-cases, and some of them want to port their bash scripts to node:
jq
?Seems hard to learn, but it really isn't.
jq
is like sed
for JSON
. Slice, filter, map and transform structured data in a simple and powerful way.
Take a look at this great introduction or a jq lesson.
You can check out the official manual and fiddle around in the online playground jqplay.org.
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