When should I name things with initial capital letters?

Question

I have always wondered when to use identifiers (for example, functions) with capital first letter instead of camel case. I always write my JS in camel case like thi

Answer 1

The convention is to name constructor functions (i.e. functions that will be used with the new keyword) with starting capital.

function MyType(simpleVar) {
    this.simpleVar = simpleVar;
}

myObject = new MyType(42);

Answer 2

The name convention states that class names are named with a first capital letter, I'm not sure how it's like with javascript, which is a prototype based language, but basically it's

class ClassName
var varName
function funcName()

Answer 3

According to the book "Javascript: the good parts", you should only capitalise the first character of the name of a function when you need to construct the object by "new" keyword.

This is called "the Constructor Invocation Pattern", a way to inherits.