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Commit 473ac64

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Object-Methods✅
1 parent c1c1bbc commit 473ac64

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let a1 = {
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name: "Suhail",
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age: 20,
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};
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let newA1 = {};
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let copy = Object.assign(newA1, a1);
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console.log(newA1);//{ name: 'Suhail', age: 20 }
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newA1.ok = "Hi"
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console.log(newA1); //{ name: 'Suhail', age: 20, ok: 'Hi' }
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console.log(copy == newA1); // true
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console.log(copy); //{ name: 'Suhail', age: 20, ok: 'Hi' }
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// It copies whole object into an new Object with a referncene one
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/*
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JavaScript Object getOwnPropertyNames()
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The JavaScript Object.getOwnPropertyNames() method returns an array of all properties found in a given object.
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The syntax of the getOwnPropertyNames() method is:
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Object.getOwnPropertyNames(obj)
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The getOwnPropertyNames() method, being a static method, is called using the Object class name.
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getOwnPropertyNames() Parameters
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The getOwnPropertyNames() method takes in:
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obj - The object whose enumerable and non-enumerable properties are to be returned.
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Return value from getOwnPropertyNames()
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Returns an array of strings that corresponds to the properties found directly in the given object.
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Note: Object.getOwnPropertyNames() returns all own properties of the object while Object.keys() returns all enumerable own properties.
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Example: Using getOwnPropertyNames()
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// array object
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let arr = ["a", "b", "c"];
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console.log(Object.getOwnPropertyNames(arr)); // [ '0', '1', '2', 'length' ]
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// array-like objects
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let obj = { 65: "A", 66: "B", 67: "C" };
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console.log(Object.getOwnPropertyNames(obj)); // [ '65', '66', '67' ]
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// non-enumerable properties are also returned
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let obj1 = Object.create(
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{},
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{
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getValue: {
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value: function () {
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return this.value;
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},
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enumerable: false,
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},
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}
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);
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obj1.value = 45;
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console.log(Object.getOwnPropertyNames(obj1)); // [ 'getValue', 'value' ]
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*/
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/*
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JavaScript Object getOwnPropertySymbols()
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The JavaScript Object.getOwnPropertySymbols() method returns an array of all symbol properties found in a given object.
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The syntax of the getOwnPropertySymbols() method is:
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Object.getOwnPropertySymbols(obj)
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The getOwnPropertySymbols() method, being a static method, is called using the Object class name.
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getOwnPropertySymbols() Parameters
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The getOwnPropertySymbols() method takes in:
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obj - The object whose symbol properties are to be returned.
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Return value from getOwnPropertySymbols()
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Returns an array of all symbol properties found directly upon the given object.
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Note: Object.getOwnPropertySymbols() returns all symbol properties of the object while Object.getOwnPropertyNames() returns the string properties
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Example: Using getOwnPropertySymbols()
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let obj = {};
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let a = Symbol("a");
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let b = Symbol.for("b");
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obj[a] = "localSymbolValue";
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obj[b] = "globalSymbolValue";
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// returns an array of symbol
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let objectSymbols = Object.getOwnPropertySymbols(obj);
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console.log(objectSymbols.length); // 2
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console.log(objectSymbols); // [Symbol(a), Symbol(b)]
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console.log(objectSymbols[0]); // Symbol(a)
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*/
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/*
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Javascript Object.getPrototypeOf()
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The JavaScript Object.getPrototypeOf() method returns the prototype of the specified object.
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The syntax of the getPrototypeOf() method is:
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Object.getPrototypeOf(obj)
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The getPrototypeOf() method, being a static method, is called using the Object class name.
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getPrototypeOf() Parameters
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The getPrototypeOf() method takes in:
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obj - The object whose prototype is to be returned.
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Return value from getPrototypeOf()
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Returns prototype of the given object.
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Returns null If there are no inherited properties.
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Example: Using Object.getPrototypeOf()
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let proto = {};
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let obj = Object.create(proto);
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console.log(Object.getPrototypeOf(obj) === proto); // true
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console.log(Object.getPrototypeOf("JavaScript"));
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// function
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let func1 = function () {};
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// creating object from function
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let object1 = Object.create(func1);
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console.log(Object.getPrototypeOf(func1) === Object.getPrototypeOf(object1)); // false
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// Object.create() creates object with given object as prototype
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console.log(func1 === Object.getPrototypeOf(object1)); // true
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*/
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/*
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JavaScript Object hasOwnProperty()
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The JavaScript Object hasOwnProperty() method checks if the object has the given property as its own property.
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The syntax of the hasOwnProperty() method is:
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obj.hasOwnProperty(prop)
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Here, obj is an object.
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hasOwnProperty() Parameters
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The hasOwnProperty() method takes in:
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prop - The String name or Symbol of the property to test.
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Return value from hasOwnProperty()
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Returns a Boolean indicating whether or not the object has the specified property as its own property.
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Notes:
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Unlike the in operator, this method does not check for a property in the object's prototype chain.
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hasOwnProperty returns true even if the value of the property is null or undefined.
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Example: Using hasOwnProperty()
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const obj = {};
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obj.property1 = 42;
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console.log(obj.hasOwnProperty("property1")); // true
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console.log(obj.hasOwnProperty("property2")); // false
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// Inherited properties return false
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console.log(obj.hasOwnProperty("toString")); // false
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*/

‎9. Object-Methods/14. Object.is().js‎

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/*
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Javascript Object.is()
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The JavaScript Object.is() method checks if two values are the same value.
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The syntax of the is() method is:
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Object.is(value1, value2)
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The is() method, being a static method, is called using the Object class name.
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is() Parameters
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The is() method takes in:
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value1 - The first value to compare.
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value2 - The second value to compare.
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Return value from is()
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Returns a Boolean indicating whether or not the two arguments are the same value.
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Two values are the same if one of the following holds:
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both undefined
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both null
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both true or both false
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both strings of the same length with the same characters in the same order
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both the same object (means both object have same reference)
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both numbers and
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both +0
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both -0
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both NaN
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or both non-zero and both not NaN and both have the same value
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Example: Using Object.is()
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// Objects with the same values
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console.log(Object.is("JavaScript", "JavaScript")); // true
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// Objects with different values
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console.log(Object.is("JavaScript", "javascript")); // false
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console.log(Object.is([], [])); // false
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let obj1 = { a: 1 };
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let obj2 = { a: 1 };
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console.log(Object.is(obj1, obj1)); // true
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console.log(Object.is(obj1, obj2)); // false
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console.log(Object.is(null, null)); // true
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// Special Cases
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console.log(Object.is(0, -0)); // false
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console.log(Object.is(-0, -0)); // true
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console.log(Object.is(NaN, 0 / 0)); // true
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*/
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/*
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JavaScript Object.isExtensible()
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The JavaScript Object.isExtensible() method checks if an object is extensible i.e. new properties can be added to it.
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The syntax of the isExtensible() method is:
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Object.isExtensible(obj)
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The isExtensible() method, being a static method, is called using the Object class name.
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isExtensible() Parameters
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The isExtensible() method takes in:
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obj - The object which should be checked.
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Return value from isExtensible()
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Returns a Boolean indicating whether or not the given object is extensible.
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Note: An object can be marked as non-extensible using Object.preventExtensions(), Object.seal(), or Object.freeze().
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Example: Using isExtensible()
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// New objects are extensible.
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let empty = {};
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console.log(Object.isExtensible(empty)); // true
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Object.preventExtensions(empty);
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console.log(Object.isExtensible(empty)); // false
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// Sealed objects are by definition non-extensible.
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let sealed = Object.seal({});
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console.log(Object.isExtensible(sealed)); // false
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// Frozen objects are also by definition non-extensible.
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let frozen = Object.freeze({});
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console.log(Object.isExtensible(frozen)); // false
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*/
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/*
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Javascript Object.isFrozen()
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The JavaScript Object.isFrozen() checks if an object is frozen.
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A frozen object can no longer be changed. Freezing an object prevents:
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New properties from being added to the object.
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Existing properties to be removed from the object.
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Changing the enumerability, configurability, or writability of existing properties.
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Changing values of the existing object properties and prototype.
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The syntax of the isFrozen() method is:
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Object.isFrozen(obj)
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The isFrozen() method, being a static method, is called using the Object class name.
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isFrozen() Parameters
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The isFrozen() method takes in:
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obj - The object which should be checked.
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Return value from isFrozen()
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Returns a Boolean indicating whether or not the given object is frozen.
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Example: Using isFrozen()
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// new objects are extensible, so not frozen
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console.log(Object.isFrozen({ name: "JavaScript" })); // false
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// preventing extensions only does not make frozen
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// property is still configurable
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let obj = { a: 1 };
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Object.preventExtensions(obj);
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console.log(Object.isFrozen(obj)); // false
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// deleting property
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delete obj.a;
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console.log(Object.isFrozen(obj)); // true -> vacuously frozen
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let newObj = { b: 2 };
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// make non-extensible
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Object.preventExtensions(newObj);
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// make non-writable
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Object.defineProperty(newObj, "b", {
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writable: false,
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});
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// properties are still configurable
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console.log(Object.isFrozen(newObj)); // false
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// using freeze()
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let frozen = { 65: "A" };
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Object.freeze(frozen);
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console.log(Object.isFrozen(frozen)); // true
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*/
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/*
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Javascript Object.isPrototypeOf()
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The JavaScript Object.isPrototypeOf() method checks if an object exists in another object's prototype chain.
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The syntax of the isPrototypeOf() method is:
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prototypeObj.isPrototypeOf(object)
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Here, prototypeObj is an object.
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isPrototypeOf() Parameters
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The isPrototypeOf() method takes in:
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object - The object whose prototype chain will be searched.
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Return value from isPrototypeOf()
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Returns a Boolean indicating whether the calling object lies in the prototype chain of the specified object.
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Note: isPrototypeOf() differs from instanceof operator as it checks the object prototype chain against prototypeObj not prototypeObj.prototype.
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Example: Using Object.isPrototypeOf()
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let obj = new Object();
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console.log(Object.prototype.isPrototypeOf(obj)); // true
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console.log(Function.prototype.isPrototypeOf(obj.toString)); // true
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console.log(Array.prototype.isPrototypeOf([2, 4, 8])); // true
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// define object
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let Animal = {
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makeSound() {
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console.log(`${this.name}, ${this.sound}!`);
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},
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};
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// new object
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function Dog(name) {
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this.name = name;
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this.sound = "bark";
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// setting prototype using setPrototypeOf()
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Object.setPrototypeOf(this, Animal);
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}
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dog1 = new Dog("Marcus");
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console.log(Animal.isPrototypeOf(dog1)); // true
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*/

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