rest_operator.html

<!DOCTYPE html>
<html>
    <head>
        <title>Rest operator uses</title>
    </head>
<body>
<h2>Rest operator uses</h2>
<script>
    /*
        Rest parameter example 1
    */
    function getFruitNames(firstName , ...lastNames) {
        console.log(firstName);
        console.log(lastNames);
    }
    getFruitNames('Mango', 'Banana', 'Apple', 'Pipneapple');

    /*
        Rest parameter example 2
    */

    // passing arguments are needed to convert array
    function multiply() {
        let arg = Array.from(arguments);
        let result = arg.reduce(function(accumulator, currentvalue) {
            return accumulator * currentvalue;
        });
        console.log(result);
    }
    multiply(1, 2);
    multiply(1, 2, 5);

    // using rest operator is no needed to convert array
    function multiply_rest(...arg) {
        let result = arg.reduce(function(accumulator, currentvalue) {
            return accumulator * currentvalue;
        });
        console.log(result);
    }
    multiply_rest(1, 2);
    multiply_rest(1, 2, 5);

    /*
        Rest parameter example 3
    */

    function sum(a, b) {
        return a + b;
    }

    console.log(sum(1, 2)); // results 3
    console.log(sum(1, 2, 5)); // results 3 becuase only taking first two parameters, other parameters are being ignored

    function sum_rest(...input){ 
        let sum = 0; 
        for(let i of input){ 
            sum+=i; 
        } 
        return sum; 
    }
    console.log(sum_rest(1, 2)); // results 3
    console.log(sum_rest(1, 2, 5)); // results 8

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