Call method in javascript

 Call() method

it is  a predefined javascript method.

with call() method , an object can use a method belonging to another object.

Using the JavaScript call() method for function borrowing

example:

var introduction1 ={

    name:"shivam",

    qualification:"B.tech",

    adress:"new delhi",

    branch:"cse",

    printintro:function()

    {

        console.log("my name is "+this.name +" and I am from " +this.adress +" and currently doing "+this.qualification+" in "+this.branch);

    }

}

console.log(introduction1);// print object

console.log(introduction1.printintro());



var introduction2={

    name:"Rj",

     qualification:"B.tech",

    adress:"mumbai",

    branch:"mechanical"

}

// i want to use method of introduction1 for our convenience

// without writing method in introduction2 object how can we use it?

// at this place a new concept come call

// we use call method 

introduction1.printintro.call(introduction2);

output:


{ name: 'shivam',

  qualification: 'B.tech',

  adress: 'new delhi',

  branch: 'cse',

  printintro: [Function: printintro] }

my name is shivam and I am from new delhi and currently doing B.tech in cse

undefined

my name is Rj and I am from mumbai and currently doing B.tech in mechanical


passing parameter

var youtuber1={

    channelname:"Istudy",

    content:"webdev",

    features: function(rating,support)

    {

        console.log(`very friendly way of teaching .${this.channelname} is my favourite ${this.content} channel. I will love to give ${rating} star. Please ${support} ${this.channelname} channel`);

    }

}

youtuber1.features(5,"subscribe");



var youtuber2={

     channelname:"studyAdda",

    content:"programming"

}

youtuber1.features.call(youtuber2,4,"subscribe")


More example discuss

const john={

    name:"john"

};

function ask()

{

    console.log(this,this.name);

}

ask(); // give globlas and undefined as output

// this point to window object

// i want to use name which is present in john object

// then we use call method

ask.call(john); // another way of calling function telling js explicitly

output ={ name: 'john' } 'john'



example 

var pokemon = {

    firstname: 'Pika',

    lastname: 'Chu ',

    getPokeName: function() {

        var fullname = this.firstname + ' ' + this.lastname;

        return fullname;

    }

};


var pokemonName = function(snack, hobby) {

    console.log(this.getPokeName() + ' loves ' + snack + ' and ' + hobby);

};


pokemonName.call(pokemon,'sushi', 'algorithms'); // Pika Chu  loves sushi and algorithms

pokemonName.apply(pokemon,['sushi', 'algorithms']); // Pika Chu  loves sushi and algorithms

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