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JavaScript - Array Basics

https://www.w3schools.com/jsref/jsref_obj_array.asp

An array is a special variable, which can hold more than one value at a time. 


var cars = ["Saab", "Volvo", "BMW"];
var cars = new Array("Saab", "Volvo", "BMW");

The two lines above to the exact same thing. You do not need to instantiate it with a new keyword. Arrays have zero-based indexes. They are start at 0. A 5 five item array has indexes 0-4.

Arrays with Objects

You can also initialize arrays with objects like so:


var ships =
[
    { property1: "value", property2: "value" },
    { property1: "value", property2: "value" }
]

 

Accessing by Indexes

You can access by the Index like so: 


var cars2 = ["Saab", "Volvo", "BMW"];
document.getElementById("demo").innerHTML = cars2[1];

 

Looping through an array

You can also loop through and array like so: 


let ships =
[
    { Name: "X Wing", Alignment: "good" },
    { Name: "Tie Fighter", Alignment: "bad" }
]

let html = "";
for (var i = 0; i < ships.length; i++)
{
    html +=ships[i].Name + " " + ships[i].Alignment + "< br />" ;
}

let demoLabel=document.getElementById("demo");
demoLabel.innerHTML=html;
results: