Get or set a deep value using a keypath string. Supports bracket and dot notation
npm install @4lolo/keypathereval` or `new Function` hacks!
Installation
`bash
npm install keypather
`
Usage
Examples
$3
`js
// modular imports, so you can keep your bundle lean
const get = require('keypather/get')
const set = require('keypather/set')
const del = require('keypather/del')
const immutableSet = require('keypather/immutable-set')
const immutableDel = require('keypather/immutable-del')
const keypathIn = require('keypather/in')
const hasKeypath = require('keypather/has')
const expand = require('keypather/expand')
const flatten = require('keypather/flatten')
`
$3
`js
const get = require('keypather/get')
const set = require('keypather/set')
const del = require('keypather/del')
let obj
// Objects
obj = { foo: { bar: 100 } }
get(obj, 'foo.bar') // returns 100
del(obj, '["foo"]["bar"]') // returns true, obj becomes { foo: {} }
set(obj, 'foo.bar.qux', 200) // returns 200, obj becomes { foo: { bar: { qux: 200 } } }
get(obj, 'foo["bar"].qux') // returns 200
// Arrays
obj = {}
set(obj, 'foo[0]', 100) // obj is { foo: [ 100 ] }
`
$3
`js
const set = require('keypather/immutable-set')
const del = require('keypather/immutable-del')
let obj
let out
// Objects
obj = { foo: { bar: 100 } }
out = set(obj, 'foo.bar', 100) // returns obj
// out === obj,
// since it was not modified
out = set(obj, 'foo.bar.qux', 200) // returns { foo: { bar: { qux: 200 } } }
// out !== obj,
// obj is still { foo: { bar: 100 } }
out = del(obj, 'one.two.three') // returns obj
// out === obj,
// since it was not modified
out = del(obj, 'foo.bar.qux') // returns { foo: { bar: {} } }
// out !== obj,
// obj is still { foo: { bar: { qux: 200 } } }
// Arrays
obj = {}
out = set(obj, 'foo[0]', 100) // returns { foo: [ 100 ] } (new)
// out !== obj, obj is still { foo: { bar: 100 } }
`
$3
`js
const hasKeypath = require('keypather/has')
const keypathIn = require('keypather/in')
const obj = { foo: Object.create({ bar: 100 }) }
hasKeypath(obj, 'foo.bar') // returns false (bar is on proto)
keypathIn(obj, 'foo.bar') // returns true
hasKeypath(obj, 'foo') // returns true
`
$3
`js
const expand = require('keypather/expand')
const flatten = require('keypather/flatten')
const obj = expand({
'foo.bar': 1,
'foo.qux[0]': 100,
'foo["qux"][1]': 200,
'foo.qux.wut': 'val'
})
// obj is { foo { bar: 1, qux: [ 100, 200, wut: 'val' ] } }
const flat = flatten(obj)
// flat is { 'foo.bar': 1, 'foo.qux': 2 } }
`
$3
`js
/ Missing deep values w/ "force: false" /
get({}, 'foo.bar', { force: false })
set({}, 'foo.bar', 100, { force: false })
del({}, 'foo.bar', { force: false })
immutableSet({}, 'foo.bar', 100, { force: false })
immutableDel({}, 'foo.bar', { force: false })
// TypeError: Cannot read property 'bar' of undefined (at keypath 'foo' of 'foo.bar')
get({ foo: {} }, 'foo.bar', { force: false })
set({ foo: {} }, 'foo.bar', 100, { force: false })
del({ foo: {} }, 'foo.bar', { force: false })
immutableSet({ foo: {} }, 'foo.bar', 100, { force: false })
immutableDel({ foo: {} }, 'foo.bar', { force: false })
// TypeError: Cannot read property 'bar' of undefined (at keypath 'foo.bar' of 'foo.bar.qux')
hasKeypath({}, 'foo.bar', { force: false })
// TypeError: Cannot read property 'hasOwnProperty' of undefined (hasOwnProperty('bar') errored at keypath 'foo' of 'foo.bar')
keypathIn({}, 'foo.bar', { force: false })
// TypeError: Cannot use 'in' operator to search for 'bar' in undefined (at 'foo' of 'foo.bar')
keypathIn({}, 'foo.bar.qux', { force: false })
hasKeypath({}, 'foo.bar.qux', { force: false })
// TypeError: Cannot read property 'bar' of undefined (at keypath 'foo' of 'foo.bar.qux')
/ Warnings for set and immutable-set /
// by default, set will overwrite primitives (string, number or regexp) to an object or array.
// when overwritePrimitives is set to false, sets will warn when settings a key on a primitive
// to disable all warnings use the option { warn: false }
set({}, '[0]', 'val', { overwritePrimitives: false })
// log: Setting number key (0) on object at keypath '' of '[0]')
set([], 'key', 'val', { overwritePrimitives: false })
// log: Setting string key 'foo' on array at keypath '' of 'foo')
set({ foo: 1 }, 'foo.qux', 'val', { overwritePrimitives: false })
// log: Setting key 'qux' on number 1 at keypath 'foo' of 'foo.qux')
set({ foo: 1 }, 'foo[0]', 'val', { overwritePrimitives: false })
// log: Setting number key (0) on number 1 at keypath 'foo' of 'foo[0]')
set({ foo: 'str' }, 'foo.bar', 'val', { overwritePrimitives: false })
// log: Setting key 'bar' on string 'str' at keypath 'foo' of 'foo.bar')
set({ foo: {} }, 'foo[0]', 'val', { overwritePrimitives: false })
// log: Setting number key (0) on object at keypath 'foo' of 'foo[0]')
/ Invalid keypaths /
get({}, 'foo.1bar')
// Error: Unexpected token '1' in keypath 'foo.1bar' at position 4 (invalid dot key)
get({}, 'foo[]')
// Error: Unexpected token ']' in keypath 'foo[]' at position 4 (invalid bracket key)
get({}, 'foo["]')
// Error: Unexpected token ']' in keypath 'foo[]' at position 5 (invalid bracket string key)
get({}, 'foo.')
// Error: Unexpected end of keypath 'foo.' (invalid dot key)
get({}, 'foo[')
// Error: Unexpected end of keypath 'foo[' (invalid bracket key)
get({}, "foo['")
// Error: Unexpected end of keypath 'foo['' (invalid bracket string key)
`
Documentation
$3
Returns value at keypath in obj
* @param {any} obj - context to read keypath from
* @param {string} keypath - bracket and/or dot notation keypath string
* @param {?object} opts - optional, defaults to { force: true }
* opts.force - force specifies whether non-existant keypaths should be ignored, defaults to true
* if false, get will error when reading a key on a non-existant keypath.
* @returns {any} value at keypath
`js
const get = require('keypather/get');
const obj = {
foo: {
bar: {
baz: 'val'
}
}
};
get(obj, "foo.bar.baz"); // returns 'val'
get(obj, "foo['bar'].baz"); // returns 'val'
get(obj, "['foo']['bar']['baz']"); // returns 'val'
get({}, 'foo.two.three', { force: false }) // throws error
// TypeError: Cannot read property 'three' of undefined (at keypath 'foo.two' of 'foo.two.three')
`
$3
Sets a value in obj at keypath. If force=true, set will create objects at non-existant keys in the
keypath. If the non-existant key is a number, its value will be initialized as an array.
* @param {any} obj - context to read keypath from
* @param {string} keypath - bracket and/or dot notation keypath string to read from obj
* @returns {any} value - value to set at keypath
* @param {?object} opts - optional, defaults to { force: true, overwritePrimitives: true, warn: true }
* opts.force - whether non-existant keys in keypath should be created, defaults to true.
* if false, set will error when reading a key on a non-existant keypath.
* opts.overwritePrimitives - whether primitive keys (booleans, strings, numbers) should be overwritten.
* setting a key on a primitive will convert it to an object or array (if key is string or number).
* if false, set will log a warning when setting keys on primitives.
* opts.silent - specifies whether warning logs should be enabled, defaults to false.
* @returns {any} value set at keypath
`js
const set = require('keypather/set');
let obj = {
foo: {
bar: {
baz: 'val'
}
}
};
set(obj, "foo['bar'].baz", 'val'); // returns 'val'
set(obj, "foo.bar.baz", 'val'); // returns 'val'
set(obj, "['foo']['bar']['baz']", 'val'); // returns 'val'
/ By default, set forces creation of non-existant keys /
obj = {}
set(obj, "foo.bar.baz", 'val'); // returns 'val'
// obj becomes:
// {
// foo: {
// bar: {
// baz: 'val'
// }
// }
// };
/ By default, overwrites primitives when setting a key on one /
obj = { foo: 1 }
set(obj, "foo.bar.baz", 'val'); // returns 'val'
// obj becomes:
// {
// foo: {
// bar: {
// baz: 'val'
// }
// }
// };
obj = { foo: 1 }
set(obj, "foo[0].baz", 'val'); // returns 'val'
// obj becomes:
// {
// foo: [{
// baz: 'val'
// }]
// };
/ Errors, force=false /
set({}, "foo.bar.baz", 'val', { force: false }); // throw's an error
// TypeError: Cannot read property 'bar' of undefined (at keypath 'foo' of 'foo.bar.baz')
// see more errors above in the 'Errors' section
/ Warnings, overwritePrimitives=false /
set({ foo: 'str' }, 'foo.bar', 'val', { overwritePrimitives: false })
// log: Setting key 'bar' on string 'str' at keypath 'foo' of 'foo.bar')
// see more warnings above in the 'Errors' section
`
$3
Deletes value a keypath in obj. Similar to delete obj.key.
* @param {any} obj - context to read keypath from
* @param {string} keypath - bracket and/or dot notation keypath string to delete from obj
* @param {?object} opts - optional, defaults to { force: true }
* opts.force - whether non-existant keys in keypath should be created, defaults to true.
* if false, del will error when reading a key on a non-existant keypath.
* @returns {boolean} true except when the property is non-configurable or in non-strict mode
`js
const del = require('keypather/del');
const obj = {
foo: {
bar: {
baz: 'val'
}
}
};
del(obj, "foo['bar'].baz"); // true
del(obj, "foo.bar.baz"); // true
del(obj, "['foo']['bar']['baz']"); // true
// obj becomes:
// {
// foo: {
// bar: {}
// }
// }
/ Errors, force=false /
del(obj, "one.two.three", 'val', { force: false }); // throw's an error
// TypeError: Cannot read property 'two' of undefined (at keypath 'one' of 'one.two.three')
// see more errors above in the 'Errors' section
`
$3
Sets a value in obj at keypath. If force=true, set will create objects at non-existant keys in the
keypath. If the non-existant key is a number, its value will be initialized as an array.
* @param {any} obj - context to read keypath from
* @param {string} keypath - bracket and/or dot notation keypath string to read from obj
* @returns {any} value - value to set at keypath
* @param {?object} opts - optional, defaults to { force: true, overwritePrimitives: true, warn: true }
* opts.force - whether non-existant keys in keypath should be created, defaults to true.
* if false, immutable-set will error when reading a key on a non-existant keypath.
* opts.overwritePrimitives - whether primitive keys (booleans, strings, numbers) should be overwritten.
* setting a key on a primitive will convert it to an object or array (if key is string or number).
* if false, immutable-set will log a warning when setting keys on primitives.
* opts.silent - specifies whether warning logs should be enabled, defaults to false.
* opts.shallowClone - provide custom shallowClone, defaults to shallow-clone
* @returns {any} returns same obj if unmodified, otherwise modified clone of obj
`js
const set = require('keypather/immutable-set');
let obj = {
foo: {
bar: {
baz: 'val'
}
}
};
let out
out = set(obj, "foo['bar'].baz", 'val'); // returns SAME object, since the value was unchanged
// out === obj
out = set(obj, "foo.bar.baz", 'val2'); // returns { foo: { bar: { baz: 'val2' } } } (new object)
// out !== obj
out = set(obj, "['foo']['bar']['baz']", 'val3'); // returns { foo: { bar: { baz: 'val3' } } } (new object)
// out !== obj
/ By default, overwrites primitives when setting a key on one /
obj = { foo: 1 }
out = set(obj, "foo.bar.baz", 'val'); // returns new object
// out !== obj
// out is:
// {
// foo: {
// bar: {
// baz: 'val'
// }
// }
// };
obj = { foo: 1 }
out = set(obj, "foo[0].baz", 'val'); // returns new object
// out !== obj
// out is:
// {
// foo: [{
// baz: 'val'
// }]
// };
/ Errors, force=false /
obj = {}
set(obj, "foo.bar.baz", 'val', { force: false }); // throws error
// Error: Cannot read property 'bar' of undefined (at keypath 'foo' of 'foo.bar.baz')
/ Warnings, force=false /
obj = { foo: 'str' }
out = set(obj, 'foo.bar', 'val', { overwritePrimitives: false })
// out === obj, since keys cannot be set on strings or numbers
// log: Setting key 'bar' on string 'str' at keypath 'foo' of 'foo.bar')
`
$3
Deletes value a keypath in obj. Similar to delete obj.key.
* @param {any} obj - context to read keypath from
* @param {string} keypath - bracket and/or dot notation keypath string to delete from obj
* @param {?object} opts - optional, defaults to { force: true }
* opts.force - whether non-existant keys in keypath should be created, defaults to true.
* if false, del will error when reading a key on a non-existant keypath.
* opts.shallowClone - provide custom shallowClone, defaults to shallow-clone
* @returns {any} returns same obj if unmodified, otherwise modified clone of obj
`js
const del = require('keypather/immutable-del');
const obj = {
foo: {
bar: {
baz: 'val'
}
}
};
let out
out = del(obj, "foo['bar'].baz"); // true
out = del(obj, "foo.bar.baz"); // true
out = del(obj, "['foo']['bar']['baz']"); // true
// obj becomes:
// {
// foo: {
// bar: {}
// }
// }
/ Errors, force=false /
del(obj, "one.two.three", 'val', { force: false }); // throw's an error
// Error: Cannot read property 'two' of undefined (at keypath 'one' of 'one.two.three')
`
$3
Returns true if keypath is "in" the obj at the keypath. Similar to "in" operator.
* @param {any} obj - context to read keypath in
* @param {string} keypath - bracket and/or dot notation keypath string to read from obj
* @param {?object} opts - optional, defaults to { force: true }
* opts.force - force specifies whether non-existant keypaths should be ignored, defaults to true
* @returns {boolean} true if the keypath is "in" the obj, else false
`js
const keypathIn = require('keypather/in');
const obj = {
foo: {
bar: {
baz: 'val'
__proto__: {
qux: 'val'
}
}
}
};
keypathIn(obj, "foo.bar.baz"); // true
keypathIn(obj, "foo.bar.qux"); // true
keypathIn(obj, "foo.bar.bing"); // false
keypathIn(obj, "foo['bar'].baz"); // true
keypathIn(obj, "one.two.three"); // false
// Errors, force=false
keypathIn(obj, "one.two.three", { force: false });
// Error: Cannot read property 'two' of undefined (at keypath 'two' of 'one.two.three')
keypathIn(obj, "foo.two.three", { force: false });
// TypeError: Cannot use 'in' operator to search for 'three' in undefined (at 'foo.two' of 'foo.two.three')
`
$3
Returns true if the obj has the keypath. Similar to obj.hasOwnProperty.
* @param {any} obj - context to read keypath in
* @param {string} keypath - bracket and/or dot notation keypath string to read from obj
* @param {?object} opts - optional, defaults to { force: true }
* opts.force - force specifies whether non-existant keypaths should be ignored, defaults to true
* @returns {boolean} true if the keypath is "in" the obj, else false
`js
const hasKeypath = require('keypather/has');
const obj = {
foo: {
bar: {
baz: 'val'
__proto__: {
qux: 'val'
}
}
}
};
hasKeypath(obj, "foo.bar.baz"); // true
hasKeypath(obj, "foo.bar.qux"); // false
hasKeypath(obj, "['foo']['bar']['baz']"); // true
hasKeypath(obj, "one.two.three"); // false
// Errors, force=false
hasKeypath(obj, "one.two.three", { force: false }); // throw's an error
// Error: Cannot read property 'two' of undefined (at keypath 'two' of 'one.two.three
hasKeypath(obj, "foo.two.three", { force: false });
// Error: Cannot read property 'hasOwnProperty' of undefined (hasOwnProperty('three') errored at keypath 'foo.two' of 'foo.two.three')
`
$3
Flatten an object or array into a keypath object
* @param {any} obj - object or array to flatten
`js
const flatten = require('keypather/flatten');
flatten({
foo: {
qux: 'hello'
},
bar: [
1,
{
yolo: [1]
}
]
});
// returns:
// {
// 'foo.qux': 'hello',
// 'bar[0]': 1,
// 'bar[1].yolo[0]': 1
// }
/ accepts a delimiter other than '.' as second arg /
flatten({
foo: {
qux: 'hello'
}
}, '_');
// returns:
// {
// 'foo_qux': 'hello',
// }
`
$3
Expand a flattened object back into an object or array
* @param {any} obj - flattened object or array to be expanded
`js
const expand = require('keypather/expand');
expand({
'foo.qux': 'hello',
'bar[0]': 1,
'bar[1].yolo[0]': 1
});
// returns:
// {
// foo: {
// qux: 'hello'
// },
// bar: [
// 1,
// {
// yolo: [1]
// }
// ]
// }
/ expand will assume an object is an array if any of the keys are numbers /
expand({
'[0]': 1,
'[1].yolo[0]': 1
});
// returns:
// [
// 1,
// {
// yolo: [1]
// }
// ]
/ accepts a delimiter other than '.' as second arg /
expand({
'foo_qux': 'hello'
}, '_');
// returns:
// {
// foo: {
// qux: 'hello'
// }
// }
``