Why Does Array Prototype Push Return The New Length Instead Of Something More Useful

Have you ever wondered why the `Array.prototype.push` method in JavaScript returns the new length of the array instead of something more obviously helpful? Well, you're not alone! This behavior can sometimes be confusing for new developers or those unfamiliar with how arrays work in JavaScript. In this article, we'll delve into the reasons behind this choice and explore some ways you can make the most of it in your coding.

First off, let's understand what the `push` method does. When you call `push` on an array in JavaScript, it adds one or more elements to the end of the array and returns the new length of the array. This can seem counterintuitive if you're coming from a language where you might expect it to return the modified array itself. However, there are some good reasons behind this design decision.

One of the key advantages of having `push` return the new length is its simplicity and efficiency. By returning just a single number, the method avoids the overhead of creating and returning a new array object every time you add an element. This can be especially important when dealing with large arrays or performance-critical code.

But how can we make the most of this behavior in practice? Well, one common pattern is to use the return value of `push` to quickly check if an element was successfully added to the array. Since `push` returns the new length of the array after the addition, you can compare this value to the previous length to see if any elements were pushed.

const myArray = [1, 2, 3];
const previousLength = myArray.length;
const newLength = myArray.push(4);

if (newLength > previousLength) {
  console.log('Element successfully added!');
} else {
  console.log('Failed to add element');
}

In this example, we store the previous length of the array before calling `push`, then compare the new length to determine if the addition was successful. This can be a handy way to handle error checking or validation when adding elements to an array.

Another useful tip is to leverage the return value of `push` in combination with other array methods. For instance, you can chain multiple `push` calls together and use the return values to track the total number of elements added:

const myArray = [];
const totalAdded = myArray.push(1, 2, 3) + myArray.push(4, 5, 6);

console.log(`Total elements added: ${totalAdded}`);

In this snippet, we combine two `push` calls and sum their return values to get the total number of elements added to the array. This can be a neat trick for concise and readable code when working with multiple additions.

In conclusion, while the choice to have `Array.prototype.push` return the new length of the array may seem a bit quirky at first, there are clear benefits to this approach in terms of simplicity and efficiency. By understanding this behavior and exploring creative ways to utilize it in your code, you can make the most of this common method in JavaScript arrays. Happy coding!