javascript-with-sai/objects.html at master · junaid537/javascript-with-sai · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //1
        function f(obj){
            console.log(obj);
        }

        let car={
            model:'mercedes',
            'car type':'racing',
            'max-speed':500
        }
        f(car);
        //2
        /*
        let x={a:1,b:2};
        */
        let x={a:1,b:2};
        delete(x.a);
        console.log(x);
        let y=x;
        //3
        y.b=7;
        console.log(y);
        console.log(x);//objects are pass by reference

        //4
        const obj4={p:1,q:2};

        const objnew=Object.assign({},obj4);//or using spread operator--->    const objnew={...obj4};

        console.log(objnew);
        document.write(obj4===objnew);//false
        document.write(Object.is(obj4,objnew));//false
        //editing objnew
        objnew.p=9;
        console.log(obj4);//no change
        console.log(objnew);
       //But its only shallow copy
       //proving shallow copy:-
       const old={p:2,q:{s:3}};
       const naya=Object.assign({},old);
       //deep changes made in 'old' causes to 'naya' also
       old.q.s=7;
        console.log(naya);//naya and old both are ====> const old={p:2,q:{s:7}};

         //FOR DEEP COPY ---------------->USE JSON.parse(JSON.stringify(old))
         const deepClone=JSON.parse(JSON.stringify(old));
         old.q.s=20;
         console.log(old);  //{p:2,q:{s:20}};

         console.log(deepClone);  //{p:2,q:{s:7}};


        //5

        /*
        Referential equality:
        if pointing to same memory address:  ==,===,Object.is()
        */
       obj1={p:1};
       obj2={p:1};

       console.log(obj1==obj2);
       console.log(obj1===obj2);
       console.log(Object.is(obj1,obj2));


       let obj3=obj1;
       console.log(obj1==obj3);
       console.log(obj1===obj3);
       console.log(Object.is(obj1,obj3));


    </script>
</body>
</html>