ES2022 JavaScript at() Method

Before getting into at() method we should know about what arrays, strings and Typed array in JavaScript is and also how to access arrays

Arrays: In JavaScript, an array is a single variable that is used to store different elements. It is often used when we want to store a list of elements and access them by a single variable. Unlike most languages where the array is a reference to the multiple variables, in JavaScript, the array is a single variable that stores multiple elements.

// Initializing while declaring
var houseNumbers = [101, 102, 103, 104, 105];

Why at() Method: Now, usually we access array elements via their indexes, and we know that the array index starts from 0.  Now if we want to access the 102 value-form above the house number array we can easily retrieve it with index = 1 which is a positive index. Now we want to access the last element of the array we cannot specify directly -1 as before ES22 the negative indexing was not supported so what we need to do is write an array name specify length function and then do -1 e.g. array_name.length-1 but after ES22 release negative index supports indexable classes.

Basically, at() methods are used to access elements of an array by specifying or passing negative indexing.

at(index): This method returns the character at the specified index. String in JavaScript has zero-based indexing. 

Parameters: This method accepts a single parameter that holds the index of the array element. The index may have positive or negative, if it is negative then it gives from the last index elements.

Example 1: 

Javascript

<script>
    // array
    const array1 = [45, 46, 47, 48, 49]
    console.log(array1.at(-1));
    console.log(array1.at(1));
</script>

Output: 

49
45

Example 2: 

Javascript

<script>
    const strarr = ["apple","ball", "cow", "dog",
        "elephant", "fish" ];
    console.log(strarr.at(-1));
    console.log(strarr.at(-3));
</script>

Output : 

fish 
dog

Advantages of using at() method:

• Improves readability of code as we do not need to specify array_name repeatedly.
• No need to use the length property to access the negative index. 

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