I'm confused why Mozilla refers to this as an Array 'Literal' when it's declared using the VARIABLE keyword and its content can be modified...
var drinks = ["Espresso", "Latte", "Cappuccino"];
Could someone shed some light on this for me?
I'm confused why Mozilla refers to this as an Array 'Literal' when it's declared using the VARIABLE keyword and its content can be modified...
var drinks = ["Espresso", "Latte", "Cappuccino"];
Could someone shed some light on this for me?
The distinction between literal and constant is crucial.
A constant remains unchanged, while a literal signifies explicitly setting the array values as a whole.
Put simply, when using a literal, you are stating what you want the array value to be in a direct manner. The literal itself (on the right side) remains constant, even though it is being assigned to a variable. Similarly, you can assign the value of a constant to a variable.
Literals exist for nearly every type of data.
var myNumber = 42; // Number literal
var myString = "Hello, world!"; // String literal
var myArray = [1, 2, 3]; // Array literal
Using square brackets like var arr = [];
to create an array is considered a literal approach, as opposed to using var arr = new Array();
In the same vein, using curly braces like {}
is a literal method for creating objects.
Literals provide a simpler way to initialize data structures compared to constructors in JavaScript.
If you search "literals vs constructors" online, you'll come across numerous resources discussing this topic :)
To delve deeper into JavaScript literals, check out this link: https://developer.mozilla.org/en/Core_JavaScript_1.5_Guide/Core_Language_Features#Literals
The specified, exact value
["Espresso", "Latte", "Cappuccino"]
remains constant -- it consists of only those three strings and nothing more. Once stored in a variable, the content of the variable can be altered, making it non-static.
You have the ability to modify the contents of the mentioned structure on the go, for instance, [4,5,6].push(7)
, however, the given value of [4,5,6]
is a specific literal that denotes an array with those particular elements.
This concept is similar to working with numerical literals, such as in b = 3 + 4
where the values 3
and 4
are immutable literals, but they can be combined to generate new outcomes (and naturally the value of b
may change).
When we use the term "literal", it signifies that the array is directly presented in its entirety. However, there are alternative methods to create the same array without using a literal approach:
let coffees = new Array();
coffees.push("French Roast");
coffees.push("Colombian");
coffees.push("Kona");
One of the key reasons why the term array literal is frequently mentioned is due to the fact that using the []
literal or the Array()
constructor does not always guarantee consistent results. This uncertainty stems from the potential for the Array()
constructor to be modified or replaced by a script. To illustrate this point:
Array = function() {
var n = 0;
for (var i=0, l=arguments.length; i<l; i++) {
n += arguments[i];
}
return n;
}
var myArray = Array(1,2,3); // The type of myArray is number with a value of 6, which may not align with your expectations
Compare this with:
var myArray = [1,2,3]; // In this case, myArray is an object with the value [1,2,3], likely more in line with what you intended
Furthermore, aside from being more concise, the literal syntax also offers complete predictability.
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