Find keys in object hierarchies using wildcard and glob matching and callbacks.
Install with npm:
$ npm install --save object-scan
const objectScan = require('object-scan');
objectScan(['a.*.f'])({ a: { b: { c: 'd' }, e: { f: 'g' } } });
// => [ 'a.e.f' ]
- Input traversed exactly once during search
- Dependency free, small in size and very performant
- Object and Array matching with e.g.
key.path
and[1]
- Wildcard matching with
*
and[*]
- Partial Wildcard matching with e.g.
mark*
,m?rk
,[*1]
or[?1]
- Arbitrary depth matching with
**
- Or-clause with e.g.
{a,b}
and[{0,1}]
- Exclusion with e.g.
!key
- Full support for escaping
- Results returned in "delete-safe" order
- Search syntax is checked for correctness
- Lots of tests to ensure correctness
A context can be passed into a search invocation as a second parameter. It is available in all callbacks and can be used to manage state across a search invocation without having to recompile the search.
By default all matched keys are returned from a search invocation. However, when it is not undefined, the context is returned instead.
Signature of all callbacks is
Fn({
key, value, parent, parents, isMatch, matchedBy, excludedBy, traversedBy, isCircular
getKey, getValue, getParent, getParents, getIsMatch, getMatchedBy, getExcludedBy, getTraversedBy, getIsCircular
context
})
where:
key
: key that callback is invoked for (respectsjoined
option).value
: value for key.parent
: current parent.parents
: array of form[parent, grandparent, ...]
.isMatch
: true iff last targeting needle exists and is non-excluding.matchedBy
: all non-excluding needles targeting key.excludedBy
: all excluding needles targeting key.traversedBy
: all needles involved in traversing key.isCircular
: true iffvalue
contained inparents
getKey
: function that returnskey
getValue
: function that returnsvalue
getParent
: function that returnsparent
getParents
: function that returnsparents
getIsMatch
: function that returnsisMatch
getMatchedBy
: function that returnsmatchedBy
getExcludedBy
: function that returnsexcludedBy
getTraversedBy
: function that returnstraversedBy
getIsCircular
: function that returnsisCircular
context
: as passed into the search
Notes on Performance:
- Arguments backed by getters use Functions Getter and should be accessed via destructuring to prevent redundant computation.
- Getters should be used to improve performance for conditional access. E.g.
if (isMatch) { getParents() ... }
. - For performance reasons, the same object is passed to all callbacks.
Type: function
Default: undefined
If defined, this callback is invoked for every match. If false
is returned, the current key is excluded from the result.
The return value of this callback has no effect when a search context is provided.
Can be used to do processing as matching keys are traversed.
Invoked in same order as matches would appear in result.
This method is conceptually similar to Array.filter().
Type: function
Default: undefined
If defined, this callback is invoked for every key that is traversed by
the search. If true
is returned, all keys nested under the current key are
skipped in the search and from the final result.
Note that breakFn
is invoked before the corresponding filterFn
might be invoked.
Type: boolean
Default: false
Keys are returned as a string when set to true
instead of as a list.
Setting this option to true
will negatively impact performance.
Note that _.get and _.set fully support lists.
Type: boolean
Default: true
When set to false
, no array selectors should be used in any needles and arrays are automatically traversed.
Note that the results still include the array selectors.
Type: boolean
Default: true
When set to false
, no errors are thrown when:
- the input contains redundant needles
More extensive examples can be found in the tests.
const objectScan = require('object-scan');
const obj = {
a: {
b: {
c: 'd'
},
e: {
f: 'g'
},
h: ['i', 'j']
},
k: 'l'
};
// top level keys
objectScan(['*'], { joined: true })(obj);
// => ["k", "a"]
// nested keys
objectScan(['a.*.f'], { joined: true })(obj);
// => ["a.e.f"]
objectScan(['*.*.*'], { joined: true })(obj);
// => ["a.e.f", "a.b.c"]
// or filter
objectScan(['a.*.{c,f}'], { joined: true })(obj);
// => ["a.e.f", "a.b.c"]
objectScan(['a.*.{c,f}'])(obj);
// => [["a", "e", "f"], ["a", "b", "c"]]
// list filter
objectScan(['*.*[*]'], { joined: true })(obj);
// => ["a.h[1]", "a.h[0]"]
objectScan(['*[*]'], { joined: true })(obj);
// => []
// deep star filter
objectScan(['**'], { joined: true })(obj);
// => ["k", "a.h[1]", "a.h[0]", "a.h", "a.e.f", "a.e", "a.b.c", "a.b", "a"]
objectScan(['**.f'], { joined: true })(obj);
// => ["a.e.f"]
objectScan(['**[*]'], { joined: true })(obj);
// => ["a.h[1]", "a.h[0]"]
// exclusion filter
objectScan(['a.*,!a.e'], { joined: true })(obj);
// => ["a.h", "a.b"]
// value function
objectScan(['**'], { filterFn: ({ value }) => typeof value === 'string', joined: true })(obj);
// => ["k", "a.h[1]", "a.h[0]", "a.e.f", "a.b.c"]
objectScan(['**'], { breakFn: ({ key }) => key === 'a.b', joined: true })(obj);
// => ["k", "a.h[1]", "a.h[0]", "a.h", "a.e.f", "a.e", "a.b", "a"]
The top level object(s) are matched by the empty needle ""
.
Useful for matching objects nested in arrays by setting useArraySelector
to false
.
Note that the empty string does not work with _.get and _.set.
The following characters are considered special and need to
be escaped if they should be matched in a key: [
, ]
, {
, }
, ,
, .
, !
, ?
, *
and \
.
Conceptually this package works as follows:
-
During initialization the needles are parsed and built into a search tree. Various information is pre-computed and stored for every node. Finally the search function is returned.
-
When the search function is invoked, the input is traversed simultaneously with the relevant nodes of the search tree. Processing multiple search tree branches in parallel allows for a single traversal of the input.
Having a separate initialization stage allows for a performant search and significant speed ups when applying the same search to different input.