Alternative to spread operator JavaScript

You can use the object assign function or apply() function as an Alternative to spread operator JavaScript.

Alternative to spread operator JavaScript

In a simple example code, the spread operator and the Object assign function both will take the right objects.

<!DOCTYPE html>
<html>
<body>

  <script>
   const moreFood = {
    'pizza': '🍕',
    'steak': '🥩',

  };

  const food = { 'chocolate': '🍫', 'icecream': '🍦', 'pizza': 'pizza' };

  var res = Object.assign(food, moreFood);

  console.log(res)

</script>

</body>
</html>

Output:

Alternative to spread operator JavaScript

There isn’t a simple one-to-one mapping between using the spread operator and using apply. But we can still create a pretty decent emulation. Let’s take a look at how.

function spreadify (fn, fnThis) {
    return function (/* accepts unlimited arguments */) {
        // Holds the processed arguments for use by `fn`
        var spreadArgs = [ ];

        // Caching length
        var length = arguments.length;

        var currentArg;

        for (var i = 0; i < length; i++) {
            currentArg = arguments[i];

            if (Array.isArray(currentArg)) {
                spreadArgs = spreadArgs.concat(currentArg);
            } else {
                spreadArgs.push(currentArg);
            }
        }

        fn.apply(fnThis, spreadArgs);
    };
}

var someArgs = ["a", "b", "c"];
var moreArgs = [1, 2, 3];


console.log(someArgs, moreArgs);

Outputs: [“a”, “b”, “c”] [1, 2, 3]

Or concatenate two arrays using concat()

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const concatenatedArray = arr1.concat(arr2);
console.log(concatenatedArray); // Output: [1, 2, 3, 4, 5, 6]

Do comment if you have any doubts or suggestions on this JS operator code.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version

Alternative to spread operator JavaScript | Example code