function_call.html

<!DOCTYPE html>
<html>
    <head>
        <title>Javascript Function Call Methods</title>
    </head>
<body>
<h2>Javascript Function Call Methods</h2>
<h3>These four methods are not applicable to arrow functions</h3>
<script>
    function show() {
        console.log(this);
        return 10;
    }

    // Method 1
    // calling unction as a function is called "Function Invocation Pattern FIP" . 
    // this  - Global object always.
    var a = show(); 
    console.log(a);


    // Method 2
    // constuctor invocation pattern CIP
    // this - newly created object
    var b = new show();
    console.log(b);

    
    // Method 3
    // method invocation pattern MIP
    // this - object before dot
    let dog = {
        name: 'abc',
        age: 8,
        canRun: function() {
            console.log(this); // this will print the object
        }
    }
    dog.canRun();

    
    // Method 4
    // manually passing value of 'this'
    // indirectly call the function, Indirect innovation pattern
    // apply, bind, call
    let animal = {
        country: 'India'
    };

    let tiger = {
        name: 'abc',
        age: 8,
        canRun: function() {
            console.log(this);
        }
    }
    tiger.canRun.call(animal);
    tiger.canRun.apply(animal);

    let lion = {
        name: 'abc',
        age: 8,
        canRun: function(param) {
            console.log(this);
            console.log(param);
        }
    }

    lion.canRun.call(animal, 'hi');
    lion.canRun.apply(animal, ['how']);


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