README

Jora

JavaScript object query engine

STATUS: Jora is still very much work in progress. Syntax may change in next releases.

Features:

Tolerant to data stucture queries (e.g. just returns nothing for paths that not reachable)
Compact syntax for common tasks
Aggregate values across arrays and eliminate duplicates by default
Stat collecting mode (powers suggestions)
Tolerant parsing mode (useful to provide suggestions for query in an editor)
Extensible DSL on query build by custom method list

Related projects:

jora-cli – Command line interface for Jora
Jora sandbox – A Web interface where you can play with jora syntax or transform some JSON with zero setup
Discovery – Uses jora to query a data for views
JsonDiscovery – a browser’s extension for viewing JSON based on Discovery, available for Chrome and Firefox (read more in the article Changing a way we’re viewing JSON in a browser)

TODO:

AST
Immutable paths hoisting (reduce computations -> performance)
Smart computation caching across queries
Query parts performance stat
Query transforming, e.g. query merge, subquery to a query, context inlining
Method namespaces, e.g. semver, path, math etc
Syntax highlighting
Prettifier
Move jison to dev dependencies
Debugging (step by step evaluation)
Input data shape prediction suitable for a query (based on touching paths)

More ideas and thoughts: Jora todo gist, Jora ToDo on Discovery.js projects state overview

Table of content:

Install
API
Quick demo
Syntax
License

Install

npm install jora

In node.js

const jora = require('jora');

For a browser unminified (dist/jora.js) and minified (dist/jora.min.js) builds are available:

<script src="node_modules/jora/dist/jora.js"></script>
<script src="node_modules/jora/dist/jora.min.js"></script>
<!-- or use one of CDN -->
<script src="https://unpkg.com/jora/dist/jora.js"></script>
<script src="https://cdn.jsdelivr.net/npm/jora/dist/jora.js"></script>

API

const jora = require('jora');

// create a query
const query = jora('foo.bar');
// or with custom methods
const queryWithCustomMethods = jora.setup({
    myMethod(current) { /* do something and return a new value */ }
});

// perform a query
const result = query(data, context);
const result = queryWithCustomMethods('foo.myMethod()')(data, context);

Options:

methods

Type: Object
Default: undefined

Additional methods for using in query passed as an object, where a key is a method name and a value is a function to perform an action. It can override build-in methods.
debug

Type: Boolean or function(name, value)
Default: false

Enables debug output. When set a function, this function will recieve a section name and its value.
tolerant

Type: Boolean
Default: false

Enables tolerant parsing mode. This mode supresses parsing errors when possible.
stat

Type: Boolean
Default: false

Enables stat mode. When mode is enabled a query stat interface is returning instead of resulting data.

Quick demo

Get npm dependency paths (as a tree) that have packages with more than one version:

const jora = require('jora');

function printTree() {
    // see implementation in examples/npm-ls.js
}

require('child_process').exec('npm ls --json', (error, stdout) => {
    if (error) {
        return;
    }

    const npmTree = JSON.parse(stdout);
    const tree = JSON.parse(stdout);
    const depsPathsToMultipleVersionPackages = jora(`
        $normalizedDeps: => dependencies.entries().({ name: key, ...value });
        $multiVersionPackages:
            ..$normalizedDeps()
            .group(=>name, =>version)
            .({ name: key, versions: value.sort() })
            .[versions.size() > 1];

        $pathToMultiVersionPackages: => .($name; {
            name,
            version,
            otherVersions: $multiVersionPackages[=>name=$name].versions - version,
            dependencies: $normalizedDeps()
                .$pathToMultiVersionPackages()
                .[name in $multiVersionPackages.name or dependencies]
        });

        $pathToMultiVersionPackages()
    `)(tree);

    printTree(depsPathsToMultipleVersionPackages);
});

Example of output:

jora@1.0.0
├─ browserify@16.2.2
│  ├─ assert@1.4.1
│  │  └─ util@0.10.3 [other versions: 0.10.4]
│  │     └─ inherits@2.0.1 [other versions: 2.0.3]
│  ├─ browser-pack@6.1.0
│  │  └─ combine-source-map@0.8.0
│  │     ├─ source-map@0.5.7 [other versions: 0.6.1, 0.4.4, 0.2.0, 0.1.43]
│  │     └─ inline-source-map@0.6.2
│  │        └─ source-map@0.5.7 [other versions: 0.6.1, 0.4.4, 0.2.0, 0.1.43]
│  ├─ browser-resolve@1.11.3
│  │  └─ resolve@1.1.7 [other versions: 1.8.1]
│  ├─ concat-stream@1.6.2
│  │  └─ inherits@2.0.3 [other versions: 2.0.1]
...

Syntax

Comments

// single-line comment
/* multi-line
comment */

Primitives

Jora	Description
42 -123 4.22 1e3 1e-2	Numbers
0xdecaf -0xC0FFEE	Hexadecimal numbers
"string" 'string'	Strings
`template line1 template line2` `template ${hello} ${world}`	Template
/regexp/ /regexp/i	A JavaScript regexp, only `i` flag supported
{ }	Object initializer/literal syntax. Spread operator (`...`) can be used, e.g. `{ a: 1, ..., ...foo }` (`...` with no expression on right side the same as `...$`)
[ ]	Array initializer/literal syntax. Spread operator (`...`) can be used, e.g. `[1, ..., ...foo]` (`...` with no expression on right side the same as `...$`). Unlike JavaScript, spread operator in jora inlines arrays only and left as is any other values, i.e. `[...[1, 2], ...3, ..."45", { "6": 7 }]` -> `[1, 2, 3, "45", { "6": 7 }]`
=> e < block > (deprecated)	A function NOTE: Syntax `< block >` is deprecated, avoid to use it
query asc query desc query asc, query desc, ...	A sorting function that takes two arguments and compare query result for each in specified order (`asc` – ascending, `desc` – descending)
query ascN query descN	The same as `asc`/`desc` but natural sorting
query ascA query descA	The same as `asc`/`desc` but reverse order for numbers
query ascAN query descAN	The same as `asc`/`desc` but natural sorting and reverse order for numbers

Keywords

Following keywords can be used with the same meaning as in JavaScript:

true
false
null
undefined
Infinity
NaN

Operators

Jora	Description
x + y	Add In case one of the operands is an array it produces new array with elements from `x` and `y` excluding duplicates
x - y	Subtract In case one of the operands is an array with elements from `x` excluding elements from `y`
x * y	Multiply
x / y	Divide
x % y	Modulo

Comparisons

Jora	Description
x = y	Equals (as `===` in JS)
x != y	Not equals (as `!==` in JS)
x < y	Less than
x <= y	Less than or equal to
x > y	Greater than
x >= y	Greater than or equal to
x ~= y	Match operator, behaviour depends on `y` type: RegExp – test against regexp function – test like `filter()` `null` or `undefined` – always truthy anything else – always falsy

Boolean logic

Jora	Description
( x )	Explicity operator precedence. Definitions are allowed (i.e. `($a: 1; $a + $a)` see bellow)
x or y	Boolean `or`. Equivalent to `\\|\\|` in JS, but `x` tests with `bool()` method
x and y	Boolean `and`. Equivalent to `&&` in JS, but `x` tests with `bool()` method
not x no x	Boolean `not`. Equivalent to `&&` in JS, but `x` tests with `bool()` method
x ? y : z	If `x` is truthy than return `y` else return `z`. `x` tests with `bool()` method
x in [a, b, c] [a, b, c] has x	Equivalent to `x = a or x = b or x = c`
x not in [a, b, c] [a, b, c] has no x	Equivalent to `x != a and x != b and x != c`

Block & definitions

Some constructions suppose to use a block, which may consists of a variable definition list (should comes first) and an expression. Both are optional. When an expression is empty, a current value (i.e. $) returns.

The syntax of definition (white spaces between any part are optional):

$ident ;
$ident : expression ;

For example:

$foo:123;          // Define `$foo` variable
$bar;              // The same as `$bar:$.bar;` or `$a: bar;`
$baz: $foo + $bar; // Definitions may be used in following expressions

In terms of JavaScript, a block creates a new scope. Once a variable is defined, its value never change. Variables can be redefined in nested scopes, but can't be duplicated in the same scope - it causes to error.

Special references

Jora	Description
$	A scope input data (current value). On top level scope it's the same as `@`. In most cases it may be omitted. Used implicitly an input for subquery when no other subjects is defined (e.g. `foo()` and `.foo()` are equivalent for `$.foo()`).
$	A reference to the second parameter of closest function or undefined when no such
@	A query input data
#	A query context

Since Jora's query performs as query(data, context), in terms of Jora it looks like query(@, #).

Path chaining

jora	Description
ident	The same as `$.ident`
.ident	Child member operator (example: `foo.bar.baz`, `#.foo['use any symbols for name']`)
..ident ..( block )	Recursive descendant operator (example: `..deps`, `..(deps + dependants)`)
.[ block ]	Filter a current data. Equivalent to a `.filter(<block>)`
.( block )	Map a current data. Equivalent to a `.map(<block>)`
method() .method() ..$method()	Invoke a method to current value, where `$method` is a reference to definition value (i.e. `$example: => $ * 10; 2.$plural(["example", "examples"])`). Can take arguments (i.e. `$method(one, 2)`).
$method() .$method() ..method()	Invoke a method to current value. See build-in methods below
path[expr]	Array-like notation to access properties. Behaves like `pick()` method. In case you need to fetch a value to each element of array use `.($[expr])` or `map(=>$[expr])`
[from:to] [from:to:step]	Slice notation. Examples: `$str: '<foo>'; str[1:-1]` (result is `'foo'`) or `$ar:[1,2,3,4,5,6]; $ar[-3::-1]` (result is `[6,5,4]`)
expr \| [definitions] expr \| ...	Pipeline operator. It's useful to make a query value as current value. Approximately this effect can be obtained using variables: `$ar: [1,2,3]; { size: $ar.size(), top2: $ar[0:2] }`. However, with pipeline operator it's a bit simplier and clear: `[1,2,3] \| { size: size(), top2: [0:2] }`

Build-in methods

jora	Description
bool()	The same as `Boolean()` in JS, with exception that empty arrays and objects with no keys treats as falsy
keys()	The same as `Object.keys()` in JS
values()	The same as `Object.values()` in JS
entries()	Similar to `Object.entries()` in JS with a difference: `{ key, value }` objects is using for entries instead of array tuples
fromEntries()	Similar to `Object.fromEntries()` in JS with difference: `{ key, value }` objects are expecting as entries instead of array tuples
pick("key") pick(index) pick(fn)	Get a value by a key, an index or a function. It returns an element with `e` index for arrays, a char with `e` index for strings, and a value with `e` key (must be own key) for enything else. Negative indecies are supported for arrays and strings. Current value is element for an array, a char for a string or an entry value for object. Arg1 (i.e. `$`) is an index for arrays and strings, and a key for objects.
size()	Returns count of keys if current data is object, otherwise returns `length` value or `0` when field is absent
sort(<fn>)	Sort an array by a value fetched with getter (`<fn>`). Keep in mind, you can use sorting function definition syntax using `asc` and `desc` keywords, qhich is more effective in many ways. In case of sorting function definition usage, `<` and `>` are not needed and you can specify sorting order for each component. Following queries are equivalents: `sort(<foo.bar>)` and `sort(foo.bar asc)` `sort(<foo>).reverse()` and `sort(foo desc)` `sort(<[a, b]>)` and `sort(a asc, b asc)`
reverse()	Reverse order of items
group(<fn>[, <fn>])	Group an array items by a value fetched with first getter.
filter(<fn>)	The same as `Array#filter()` in JS
map(<fn>)	The same as `Array#map()` in JS
split(pattern)	The same as `String#split()` in JS. `pattern` may be a string or regexp
join(separator)	The same as `Array#join()` in JS. When `separator` is undefined then `","` is using
slice(from, to)	The same as `Array#slice()` or `String#slice()` in JS
match(pattern, matchAll)	Similar to `String#match()`. Since regexp'es in jora doesn't support for `g` flag, use `matchAll` argument to get all matches, i.e. `'abcabc'.match(/ab/, true)` (jora) instead of `'abcabc'.match(/ab/g)` (JS)
reduce(fn[, initValue])	The same as `Array#reduce()` in JS. Use `$` to access to accumulator and `$` to current value, e.g. find the max value `reduce(=>$ > $ ? $ : $)`

License

MIT

Usage no npm install needed!