TypeScript - Global Functions

Class-less functions. You should evaluate and determine:

• "Does this functionality really need to be in a Class?"
• "Can it/should it be shared throughout the app?"

You may want a Global Function and not a Class Function. Defining functions NOT within a class. These are considered GLOBAL functions. Not restricted to be within a class. You can mouse-over this function and see that it outputs a number because the arguments are numbers.

// Example 1
let CalculateMillage = function (lightYearsTraveled: number, gallons: number)
{
    return lightYearsTraveled / gallons;
}

// Example 2
// Here is a 'short cut' to write the same thing. This uses arrow function and omits the keyword 'function'.
let CalculateMillage2 = (lightYearsTraveled: number, gallons: number) => lightYearsTraveled / gallons;

window.onload = function ()
{
    let LightYearsPerGallonLabel = <HTMLElement>document.getElementById("light-years-per-gallon");
    LightYearsPerGallonLabel.innerHTML = "Light Years Per Gallon: " + CalculateMillage(100, 3);

    let LightYearsPerGallonLabel2 = <HTMLElement>document.getElementById("light-years-per-gallon-2");
    LightYearsPerGallonLabel2.innerHTML = "Light Years Per Gallon: " + CalculateMillage2(100, 2.3);
};