awesome-cheatsheets/languages/javascript/objects.js

/* *******************************************************************************************
 * GLOBAL OBJECTS > OBJECT
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
 * ******************************************************************************************* */

// Global object: properties
Object.length                                         // length is a property of a function object, and indicates how many arguments the function expects, i.e. the number of formal parameters. This number does not include the rest parameter. Has a value of 1.
Object.prototype                                     // Represents the Object prototype object and allows to add new properties and methods to all objects of type Object.

// Methods of the Object constructor
Object.assign(target, ...sources)                    // Copies the values of all enumerable own properties from one or more source objects to a target object. method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object
Object.create(MyObject)                              // Creates a new object with the specified prototype object and properties. The object which should be the prototype of the newly-created object.
Object.defineProperty(obj, prop, descriptor)         // Adds the named property described by a given descriptor to an object.
Object.defineProperties(obj, props)                  // Adds the named properties described by the given descriptors to an object.
Object.entries(obj)                                  // Returns an array containing all of the [key, value] pairs of a given object's own enumerable string properties.
Object.freeze(obj)                                   // Freezes an object: other code can't delete or change any properties.
Object.getOwnPropertyDescriptor(obj, prop)           // Returns a property descriptor for a named property on an object.
Object.getOwnPropertyDescriptors(obj)                // Returns an object containing all own property descriptors for an object.
Object.getOwnPropertyNames(obj)                      // Returns an array containing the names of all of the given object's own enumerable and non-enumerable properties.
Object.getOwnPropertySymbols(obj)                    // Returns an array of all symbol properties found directly upon a given object.
Object.getPrototypeOf(obj)                           // Returns the prototype of the specified object.
Object.is(value1, value2);                           // Compares if two values are the same value. Equates all NaN values (which differs from both Abstract Equality Comparison and Strict Equality Comparison).
Object.isExtensible(obj)                             // Determines if extending of an object is allowed.
Object.isFrozen(obj)                                 // Determines if an object was frozen.
Object.isSealed(obj)                                 // Determines if an object is sealed.
Object.keys(obj)                                     // Returns an array containing the names of all of the given object's own enumerable string properties.
Object.preventExtensions(obj)                        // Prevents any extensions of an object.
Object.seal(obj)                                     // Prevents other code from deleting properties of an object.
Object.setPrototypeOf(obj, prototype)                // Sets the prototype (i.e., the internal [[Prototype]] property).
Object.values(obj)                                   // Returns an array containing the values that correspond to all of a given object's own enumerable string properties.

// Object instances and Object prototype object (Object.prototype.property or Object.prototype.method())
// Properties
obj.constructor                                      // Specifies the function that creates an object's prototype.
obj.__proto__                                        // Points to the object which was used as prototype when the object was instantiated.

// Methods
obj.hasOwnProperty(prop)                             // Returns a boolean indicating whether an object contains the specified property as a direct property of that object and not inherited through the prototype chain.
prototypeObj.isPrototypeOf(object)                   // Returns a boolean indicating whether the object this method is called upon is in the prototype chain of the specified object.
obj.propertyIsEnumerable(prop)                       // Returns a boolean indicating if the internal ECMAScript [[Enumerable]] attribute is set.
obj.toLocaleString()                                 // Calls toString().
obj.toString()                                       // Returns a string representation of the object.
object.valueOf()                                     // Returns the primitive value of the specified object.