object

Object utilities.

Table of Contents #

contains(obj, value):Boolean #

Similar to Array/contains. Checks if Object contains value.


var obj = {
    a: 1,
    b: 2,
    c: 'bar'
};
contains(obj, 2);      // true
contains(obj, 'foo');  // false

deepEquals(a, b):Boolean #

Recursively tests whether two objects contain the same keys and values.

Tests whether the objects contain the same keys and equal values. If the values are both an object, it will recurse into the objects, checking if their keys/values are equal.

It will only check the keys and values contained by the objects; it will not check the objects' prototypes. If the either of the values are not objects, they will be checked using the === operator.

Example:


deepEquals({ a: 1 }, { a: 1 }); // true
deepEquals({ value: { a: 1 } }, { value: { a: 1 } }); // true
deepEquals({ value: { a: 1 } }, { value: { a: 2 } }); // false
deepEquals({ value: { a: 1 } }, { value: { a: 1, b: 2 } }); // false
deepEquals({}, null); // false
deepEquals(null, null); // true

See: equals()

deepFillIn(target, ...objects):Object #

Fill missing properties recursively.

It's different from deepMixIn since it won't override any existing property. It's also different from merge since it won't clone child objects during the process.

It returns the target object and mutates it in place.

See: fillIn(), deepMixIn(), merge()


var base = {
    foo : {
        bar : 123
    },
    lorem : 'ipsum'
};
var options = deepFillIn({foo : { baz : 45 }, lorem : 'amet'}, base);
// > {foo: {bar:123, baz : 45}, lorem : 'amet'}

deepMixIn(target, ...objects):Object #

Mixes objects into the target object, recursively mixing existing child objects as well.

It will only recursively mix objects if both (existing and new) values are plain objects.

Returns the target object. Like merge(), but mutates the target object, and does not clone child objects.


var target = {
    foo: {
        name: "foo",
        id: 1
    }
};

deepMixIn(target, { foo: { id: 2 } });
console.log(target); // { foo: { name: "foo", id: 2 } }

See: mixIn(), merge(), deepFillIn()

equals(a, b):Boolean #

Tests whether two objects contain the same keys and values.

It will only check the keys and values contained by the objects; it will not check the objects' prototypes. If either of the values are not objects, they will be compared using the === operator.


equals({}, {}); // true
equals({ a: 1 }, { a: 1 }); // true
equals({ a: 1 }, { a: 2 }); // false
equals({ a: 1, b: 2 }, { a: 1 }); // false
equals({ a: 1 }, { a: 1, b: 2 }); // false
equals(null, null); // true
equals(null, {}); // false

every(obj, callback, [thisObj]):Boolean #

Similar to Array/every. Tests whether all properties in the object pass the test implemented by the provided callback.


var obj = {
    a: 1,
    b: 2,
    c: 3,
    d: 'string'
};

every(obj, isNumber); // false

fillIn(obj, ...default):Object #

Fill in missing properties in object with values from the defaults objects.

var base = {
    foo : 'bar',
    num : 123
};

fillIn({foo:'ipsum'}, base); // {foo:'ipsum', num:123}

PS: it allows merging multiple objects at once, the first ones will take precedence.

See: mixIn(), merge(), deepFillIn()

filter(obj, callback, [thisObj]) #

Returns a new object containing all properties where callback returns true, similar to Array/filter. It does not use properties from the object's prototype.

Callback receives the same arguments as forOwn().

See: forOwn(), forIn(), pick()


var obj = {
    foo: 'value',
    bar: 'bar value'
};

// returns { bar: 'bar value' }
filter(obj, function(v) { return value.length > 5; });

// returns { foo: 'value' }
filter(obj, function(v, k) { return k === 'foo'; });

find(obj, callback, [thisObj]) #

Loops through all the properties in the Object and returns the first one that passes a truth test (callback), similar to Array/find. Unlike Array/find, order of iteration is not guaranteed.


var obj = {
    a: 'foo',
    b: 12
};

find(obj, isString); // 'foo'
find(obj, isNumber); // 12

forIn(obj, callback[, thisObj]) #

Iterate over all properties of an Object, similar to Array/forEach.

It avoids don't enum bug on IE. It will iterate over inherited (enumerable) properties from the prototype.

It allows exiting the iteration early by returning false on the callback.

See: forOwn(), keys(), values()

Callback arguments

Callback will receive the following arguments:

  1. Property Value (*)
  2. Key name (String)
  3. Target object (Object)

Example


function Foo(){
    this.foo = 1;
    this.bar = 2;
}

Foo.prototype.lorem = 4;

var obj = new Foo();

var result = 0;
var keys = [];

forIn(obj, function(val, key, o){
    result += val;
    keys.push(key);
});

console.log(result); // 7
console.log(keys);   // ['foo', 'bar', 'lorem']

forOwn(obj, callback[, thisObj]) #

Iterate over all own properties from an Object, similar to Array/forEach.

It avoids don't enum bug on IE. Notice that it won't iterate over properties from the prototype.

It allows exiting the iteration early by returning false on the callback.

See: forIn(), keys(), values()

Callback arguments

Callback will receive the following arguments:

  1. Property Value (*)
  2. Key name (String)
  3. Target object (Object)

Example


function Foo(){
    this.foo = 1;
    this.bar = 2;
}

// will be ignored
Foo.prototype.lorem = 4;

var obj = new Foo();

var result = 0;
var keys = [];

forOwn(obj, function(val, key, o){
    result += val;
    keys.push(key);
});

console.log(result); // 3
console.log(keys);   // ['foo', 'bar']

get(obj, propName):* #

Returns nested property value. Will return undefined if property doesn't exist.

See: set(), namespace(), has()


var lorem = {
        ipsum : {
            dolor : {
                sit : 'amet'
            }
        }
    };

get(lorem, 'ipsum.dolor.sit'); // "amet"
get(lorem, 'foo.bar');         // undefined

has(obj, propName):Boolean #

Checks if object contains a child property. Useful for cases where you need to check if an object contain a nested property. It will get properties inherited by the prototype.

see: hasOwn(), get()


var a = {
        b : {
            c : 123
        }
    };

has(a, 'b.c');   // true
has(a, 'foo.c'); // false

Common use case


if( has(a, 'foo.c') ){ // false
    // ...
}

if( a.foo.c ){ // ReferenceError: `foo` is not defined
    // ...
}

hasOwn(obj, propName):Boolean #

Safer Object.hasOwnProperty. Returns a boolean indicating whether the object has the specified property.

see: has()


var obj = {
    foo: 1,
    hasOwnProperty : 'bar'
};

obj.hasOwnProperty('foo'); // ERROR! hasOwnProperty is not a function

hasOwn(obj, 'foo');            // true
hasOwn(obj, 'hasOwnProperty'); // true
hasOwn(obj, 'toString');       // false

keys(obj):Array #

Returns an array of all own enumerable properties found upon a given object. It will use the native Object.keys if present.

PS: it won't return properties from the prototype.

See: forOwn(), values()


var obj = {
    foo : 1,
    bar : 2,
    lorem : 3
};
keys(obj); // ['foo', 'bar', 'lorem']

map(obj, callback, [thisObj]):Object #

Returns a new object where the property values are the result of calling the callback for each property in the original object, similar to Array/map.

The callback function receives the same arguments as in forOwn().

See: forOwn()


var obj = { foo: 1, bar: 2 },
    data = { foo: 0, bar: 1 };

map(obj, function(v) { return v + 1; }); // { foo: 2, bar: 3 }
map(obj, function(v, k) { return k; }); // { foo: "foo", bar: "bar" }
map(obj, function(v, k) { return this[k]; }, data); // { foo: 0, bar: 1 }

matches(obj, props):Boolean #

Checks if object contains all properties/values pairs. Useful for validation and filtering.


var john = {age:25, hair:'long', beard:true};
var mark = {age:27, hair:'short', beard:false};
var hippie = {hair:'long', beard:true};
matches(john, hippie); // true
matches(mark, hippie); // false

merge(...objects):Object #

Deep merges objects. Note that objects and properties will be cloned during the process to avoid undesired side effects. It return a new object and won't affect source objects.


var obj1 = {a: {b: 1, c: 1, d: {e: 1, f: 1}}};
var obj2 = {a: {b: 2, d : {f : 'yeah'} }};

merge(obj1, obj2); // {a: {b : 2, c : 1, d : {e : 1, f : 'yeah'}}}

See: deepMixIn(), deepFillIn()

max(obj[, iterator]):* #

Returns maximum value inside object or use a custom iterator to define how items should be compared. Similar to Array/max.

See: min()


max({a: 100, b: 2, c: 1, d: 3, e: 200}); // 200
max({a: 'foo', b: 'lorem', c: 'amet'}, function(val){
    return val.length;
}); // 'lorem'

min(obj[, iterator]):* #

Returns minimum value inside object or use a custom iterator to define how items should be compared. Similar to Array/min.

See: max()


min({a: 100, b: 2, c: 1, d: 3, e: 200}); // 1
min({a: 'foo', b: 'lorem', c: 'amet'}, function(val){
    return val.length;
}); // 'foo'

mixIn(target, ...objects):Object #

Combine properties from all the objects into first one.

This method affects target object in place, if you want to create a new Object pass an empty object as first parameter.

Arguments

  1. target (Object) : Target Object.
  2. ...objects (...Object) : Objects to be combined (0...n objects).

Example


var a = {foo: "bar"};
var b = {lorem: 123};

mixIn({}, a, b); // {foo: "bar", lorem: 123}
console.log(a);  // {foo: "bar"}

mixIn(a, b);     // {foo: "bar", lorem: 123}
console.log(a);  // {foo: "bar", lorem: 123}

See: fillIn(), merge()

namespace(obj, propName):Object #

Creates an empty object inside namespace if not existent. Will return created object or existing object.

See: get(), set()


var obj = {};
namespace(obj, 'foo.bar'); // {}
console.log(obj);          // {foo:{bar:{}}}

pick(obj, ...keys):Object #

Return a copy of the object that contains only the whitelisted keys.

See: filter()


var user = {
    firstName : 'John',
    lastName : 'Doe',
    dob : '1985/07/23',
    gender : 'male'
};

// can pass an array of keys as second argument
var keys = ['firstName', 'dob']
pick(user, keys); // {firstName:"John", dob: "1985/07/23"}

// or multiple arguments
pick(user, 'firstName', 'lastName'); // {firstName:"John", lastName: "Doe"}

pluck(obj, propName):Object #

Extract an object containing property values with keys as they appear in the passed object.


var users = {
    first: {
        name : 'John',
        age : 21
    },
    second: {
        name : 'Mary',
        age : 25
    }
};

pluck(users, 'name'); // {first: 'John', second: 'Mary'} );
pluck(users, 'age');  // {first: 21, second: 25} );

reduce(obj, callback, initial, [thisObj]):* #

Similar to Array/reduce.

Apply a function against an accumulator and each property of the object (order is undefined) as to reduce it to a single value.


var obj = {a: 1, b: 2, c: 3, d: 4};

function sum(prev, cur, key, list) {
    compare1.push(prev);
    return prev + cur;
}

reduce(obj, sum); // 10

reject(obj, callback, thisObj):Object #

Returns a new object containing all properties where callback returns true, similar to Array/reject. It does not use properties from the object's prototype. Opposite of filter().

See filter()

Example


var obj = {a: 1, b: 2, c: 3, d: 4, e: 5};
reject(obj, function(x) { return (x % 2) !== 0; }); // {b: 2, d: 4}

values(obj):Array #

Returns an array of all own enumerable properties values found upon a given object.

PS: it won't return properties from the prototype.

See: forOwn(), keys()


var obj = {
    foo : 1,
    bar : 2,
    lorem : 3
};
values(obj); // [1, 2, 3]

set(obj, propName, value) #

Sets a nested property value.

See: get(), namespace()


var obj = {};
set(obj, 'foo.bar', 123);
console.log(obj.foo.bar); // 123
console.log(obj);         // {foo:{bar:123}}

size(obj):Number #

Returns the count of own enumerable properties found upon a given object.

PS: it won't return properties from the prototype.

See: forOwn(), keys()


var obj = {
    foo : 1,
    bar : 2,
    lorem : 3
};
size(obj); // 3

some(obj, callback, [thisObj]):Boolean #

Similar to Array/some. Tests whether any properties in the object pass the test implemented by the provided callback.


var obj = {
    a: 1,
    b: 2,
    c: 3,
    d: 'string'
};

some(obj, isNumber); // true

unset(obj, propName):Boolean #

Delete object property if existent and returns a boolean indicating succes. It will also return true if property doesn't exist.

Some properties can't be deleted, to understand why check this article.

See: set()


var lorem = {
        ipsum : {
            dolor : {
                sit : 'amet'
            }
        }
    };

unset(lorem, 'ipsum.dolor.sit'); // true
console.log(lorem.ipsum.dolor);  // {}
unset(lorem, 'foo.bar');         // true
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