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ways of defining object js
<![CDATA[1) Object Literal
const obj = {
name: "Ram",
age: "20"
}
2) Constructor Function or ES6- Class
const a = new Person("Ram", "25") //given Person is an existing function or class
3) Object.create method
const ram = Object.create(Person); //given person is an existing object]]>
object to array javascript
<![CDATA[Object.values(obj)]]>
object object javascript
<![CDATA[person = {
'name':'john smith'
'age':41
};
console.log(person);
//this will return [object Object]
//use
console.log(JSON.stringify(person));
//instead]]>
js object
<![CDATA[var person = {
"name" : "Mrs. White"
};]]>
show filed of object javascript
<![CDATA[var getKeys = function(obj){
var keys = [];
for(var key in obj){
keys.push(key);
}
return keys;
}]]>
javascript object
<![CDATA[/*
An object is made of key value pairs. Keys can be strings
(which don't require quotes), array with a string, or symbols. Values can be arrays,
objects, numbers etc
*/
let testSymbol = Symbol('item number 3')
const obj = {
item1: 1,
"item number 2": 2,
testSymbol: 3,
['a']: 4
}
// Another way of creating an object:
const obj = new Object();
obj.name = 'John'
// To access values, you can use dot notation or bracket notation.
// Both do the same thing, bracket notion is useful for multispace keys,
// keys with dashes, or accessing values using variables
> obj.item1
> obj['item number 2']
> let b = 'item1'
obj[b]
// The following would NOT work and would return undefined:
obj.b
// Checking exsistence of keys in object:
obj.toString ----- checks values of object and whatever object inherits from
> returns true
obj.hasOwnProperty('toString') ----- checks values of object only. Do this instead of checking like: (obj.name !== undefined)
> returns false
// Short hand key assignment:
const name = 'John'
const obj2 = {
// this is short hand that automatically sets the key to be 'name',
// and it's value to be 'John'
name,
}
// Constructor objects:
function Obj(name, age){
this.name = name
this.age = age
}
const person = new Obj('john', 1)
// adding functions, couple ways:
const obj = {
name: 'Mike',
number: 4421,
sayHi: () => console.log('hi'),
sayBye() {
console.log('say bye')
},
// getter function to get values from object. Has different usecases, but the same as doing obj.number
get getNumber(){
return this.number
}
// setter function to set values in object. Has different usecases, but the same as doing obj.number = 152
set setNumber(num){
this.number = num
}
}
obj.sayHi()
obj.sayBye()
obj.getNumber //Note how it's being accessed like a standard property, and not a function
obj.setNumber //Note how it's being accessed like a standard property, and not a function]]>
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