CRUD Operations

	Syntax	Example
Create	let obj = new Object() // Object constructor syntax let obj = {} // Object literal syntax	let user = new Object(); let user= {a:1,b:2};
Read	obj[key]	user['a'] //`1`
Update
Replace	obj[key]=value	user[‘a’]=5; user["multi key"]=4; //`{a: 5, b: 2}`
	obj.key=value	user.a=7; //`{a: 7, b: 2}`
Add	obj[key]=value	user.c=3; user["multi key"]=4; //`{a: 7, b: 2, c: 3, multi key: 4}`
Delete
Delete object property	delete obj[key]	delete user.a; //`{b: 2, c: 3, multi key: 4}`
Delete/Reset entire object	Garbage collector deletes object when not referenced

Object Iteration/ Copy

	Syntax	Example
Copy	let obj2=obj1 //copied by reference #	let obj1={a:1,b:{x:1}}; let obj2=obj1; obj2.a=2; console.log(obj1); //`{a: 2, b: {x:1}}`
	let obj2=Object.assign({},obj1) //shallow copy - only primitives are copied Let obj2= {...obj1} //shallow copy	let obj3=Object.assign({},obj1); obj3.a=7,obj3.b.x=7; console.log(obj1); //`{a: 5, b: {x:7}`
	let obj2= JSON.parse(JSON.stringify(obj1)) //deep copy	let obj4=JSON.parse(JSON.stringify(obj1)); obj4.a=6,obj4.b.x=6; console.log(obj1); //`{a: 5, b: {x:7}`
Iteration	For key in object //iterating over keys	let obj={a:1,b:2}; for(key in obj)console.log(key);// `a b`
	If key in object //checking if key exists	if('a' in obj) console.log("yes"); // `yes`
	Object.keys(obj)	Object.keys(obj); //`["a", "b"]`
	Object.values(obj)	Object.values(obj); //`[1, 2]`
	Object.entries(obj)	Object.entries(obj); //`[[“a”,1],[“b”,2]]`
Delete/Reset entire object	Garbage collector deletes object when not referenced

Operation	Syntax/Example
Count	Object.keys(obj).length;
Max of object value	let max=0; for(let[key,value] of Object.entries(obj)){ if(max<value) max=value; } console.log(max); // `2`
Count of same object properties in an array	Sample Input: [{x:1,y:1},{x:2,y:3},{x:4,y:4}] Sample Output: 2 obj.reduce((target,item)=>{if(item.x==item.y) target+=1; return target;},0) //`2`