Parentheses are uses for a few different functions, here are some examples below

Grouping expressions:

a + (b * c)

Containing expressions:

(x % 2 == 0)

Containing a list of parameters:

functionName(parameter1, parameter2, parameter3) { code to be executed}

Square brackets provide access to an object’s properties, for example, bracket notion:

object[“property”]

Arrays contain a list of data, which is wrapped in square brackets:

var cars = [“Saab”, “Volvo”, “BMW”];

Arrays within arrays:

var items = [[1, 2],[3, 4],[5, 6]];

It important to understand how to use quotes appropriotly in JS. We should use single quotes where you want double quotes to appear inside the string, (e.g. for a html attributes), without having to escape them, or vice versa. Other than that, there is no difference. He is an example.

var answer = "He is called 'Johnny'"; var answer = 'He is called "Johnny"';

Either single or double can be used, as long as you are consistant. Below is am example of an object itural, in single quotes:

var myObject = { prop_a: ‘some string value’, prop_b: ‘string value’, int_prop: 100 };

Either double or single can be used, as long as you are consistant. Example of double quotes:

var carname = “Volvo XC60”;