Variables

A variable is a container that holds a value. You must give it a name, and then you can use this name to refer to the value stored inside it.

info

OneVision Scripts builds on JavaScript by adding a feature called static typing which makes it easier to write safe and error-free code.

Let's explore the variable's basics:

Declaring variables

In OneVision Scripts, you can declare different types of variables using different keywords:

• var: Declares a variable that can be used throughout the entire script it’s declared in.
• global var: Adding global to the variable defintion makes the it usable in all scripts. This means that it can be read or modified in any script, and by any function or block.
• const var / const global var: Adding const to the variable definition makes it read only. This means the variable cannot be modified anywere in the code. This is specially useful to define configuration parameters.
• pglobal var: Adding pglobal to the variable definition makes the variable permanent global. This means it is a global variable that will keep the value after stopping the runtime.

For example:

var a = 5; 
global var b = 10; 
const var c = 15; 
const global var d = 20;
pglobal var e = 25;

Variable types

Variables may hold values that have different data types:

Type	Description	Example
number	Numeric values, including integers and floating-point numbers.	var num = 42;
string	Textual data, sequences of characters enclosed in quotes.	var str = "Hello, world!";
boolean	Logical values. Possible values are true and false.	var isTrue = true;
list	Ordered collections of values. Allows storing multiple elements in a single reference.	var list = [1, 2, 3, 4, 5];
object	Unordered and static collections of key-value pairs.	var obj = {item1: 23, item2: "apple", item3: true};
record	Unordered and dynamic collections of key-value pairs.	var rec: Record<string, number[]> = {"a": [1, 2, 3], "b": [4]};
any	Allows to define a variable when the type is unknown.	var mixedList: any[] = [1, "Hello", true];

Adding types to variables

OneVision Scripts allows you to specify what type of data a variable will hold. This is called a type annotation.

var age: number = 30; // age must be a number
var name: string = "Alice"; // name must be a string
var isStudent: boolean = true; // isStudent must be a boolean (true or false)

OneVision Scripts is smart and can guess the type of a variable based on the value you give it, so you don't have to explicitly state the type. This is called type inference.

var city = "Barcelona"; // OneVision knows 'city' is a string
var score = 100; // OneVision knows 'score' is a number

You can also declare lists with a specific type.

var scores: number[] = [90, 85, 88]; // array of numbers
var players: string[] = ["Maqsood Ahmed", "Gogi Alauddin", "Ibrahim Amin"]; // array of strings

OneVision can infer the type of lists as well.

var scores = [90, 85, 88]; // OneVision knows the variable scores will contain a list of numbers

caution

You cannot declare a variable with an empty list.

var players = []; // Error

Define the type of the list to declare an empty list.

var players: string[] = []; // Correct

Type Assertions

Sometimes you know more about the type of a variable than OneVision Scripts does. You can use type assertions to specify the type you know it should be.

var someValue: any = "this is a string";
var strValue: string = someValue as string;