There are nine units in Lambda School’s Full Stack Web Development Pre-course. I’m going to summarize what the pre-course covers for each of them. This material is basically ground-floor information that students need to know before they start the full course.

Learn to use Math, Properties, Methods and Global Objects in JavaScript

All of my adult life, and most of my younger life, I’ve heard that you need to study math to be a programmer. I’ve worked with developers for years who are wizards at math, but I’m not particularly adept, although I’m not incompetent either. This course might begin to show me how necessary math is to programming, and if it is – what types of math and to what areas of programming.

At work, we do use math in our software for performing clinical calculations. For example, there are several standards for determining percentage of weight change (gain or loss) and related to that are calculations for caloric intake and calories burned that are part of our nutritional assessment, for dieticians. This has modifiers for if the patient has certain conditions, like recovering from various injuries (say, skeletal trauma has a particular weight that modifies the total score), activity factor and other things. Data like this then computes things like maintenance calories (how many calories a patient needs each day to stay at their current weight), estimated protein needs, estimated fluid needs, and so on.

Nurses have their own math-related concerns that they track with our software, often related to pressure ulcers or other wounds, patterns of oral consumption – which can affect weight (a big concern for both nursing and dietary), and formulas related to ADL’s (Activities of Daily Living) which can impact how much money a nursing home is paid for support, per resident. The finance side has a TON of math which ties in to every clinical department’s work – social work’s psychological assessments, therapeutic activities’ work with the resident, and so on. There are a lot of modifiers to consider when viewing a patient’s entire situation and the impact it has on revenue for a facility as well as tracking changes when moving to and from hospitals and other nursing homes.

With that out of the way, JavaScript, like all other programming languages that I’m aware of, has the ability to solve math problems. Solving math is actually one of the core functions of a computer. I know that numbers control everything on a screen, to some extent. The pixels we look at are on a 2-dimensional grid. 3D graphics require a bit of processing and there are definitely equations running in the background determining how these moving 3-dimensional objects maintain form and motion – which then adds a physics engine on top of that, which is powered by more math, and so on.

As someone who hasn’t programmed on that level, I’ve never had to deal with any of this at work. Aside from using numbers to add padding, space, control font sizes, and that sort of thing to various sections of our application’s interface, I can’t say I’ve thought about anything even as basic as a Pythagorean Theorem since high school. I’ve researched formulas for assessment sections that need them, but all of this is math that was done by someone else that I helped determine needed to be incorporated into our program. The development team took it to the next level and actually… did the math and made it work successfully. Maybe this course will change my perception about how heavily math is needed for programming. Right now, I think that acting on the value of a piece of data, and on user input, is more important.

Math Operators

JavaScript has operators that perform the 4 basic math functions that we all had to learn as children: addition, subtraction, multiplication and division. There’s a 5th basic function as well now, called modulo. Its just the remainder, left over from doing division – so the modulo of 5/2 is 1, because 2 into 5 is 2, with 1 left over. The keyboard characters that we use for basic math are as follows:

+ for addition: 1 + 1 = 2
- for subtraction: 3 - 2 = 1
* for multiplication: 3 * 2 = 6
/ for division, and: 10 / 2 = 5
% for modulo: 9 % 3 = 0

Properties and Methods

As per the Lambda School text:

Primitive data types (and other data types) have built-in functionality known as properties and methods. These extend the functionality of the primitive data types and allow us to gather information about them, or manipulate them in some way. Both properties and methods will be accessed using the dot notation where we give the name of the variable, a dot, then the name of the property or method.

variableName.propertyName;

Properties

Properties are essentially metadata about a variable – things like the length (number of characters) in a string, for example. According to w3schools, its possible to add custom properties to a variable. For example, a variable called electricBass could have properties like brand, stringNum, handedness, and so on.

In accordance with the dot notation described in the Lambda School text, those properties would be accessed by the following names:

electricBass.brand
electricBass.stringNum
electricBass.handedness

Going along with the bass analogy, some possible values for brand could be “Fender”, “Gibson”, “Schecter” or “Ibanez”. Values for stringNum could include 4, 5, 6, 7 or 8 (yes, I know Jaco only needed 4 strings). Values for handedness could be “left” or “right”.

The example below gives us the length of a string, or how many characters it contains (spaces count).

const favoriteSteak = 'ribeye';
favoriteSteak.length; //6

Methods

A method is essentially a function or action that can be embedded or placed inside of a variable (or other object, apparently). Methods allow customized actions to be performed on specific variables or data types. They’re called like properties, but with an additional set of parenthesis at the end. For example:

var dialogue = "Hello! My name is Inigo Montoya. You killed my father... 
  prepare to die!";
var x = message.toUpperCase();

The above would return:

HELLO! MY NAME IS INIGO MONTOYA. YOU KILLED MY FATHER... 
PREPARE TO DIE!

Global objects and methods

As per the Lambda School text:

JavaScript has a number of built-in objects for us to use. These global objects extend the functionality of the language for us for free. We have already seen, and have been using, the console object and its method log. Another one of these objects is Math. Math has a number of methods on it just like console has log. To add to this, some of our data types also have built-in methods.

• w3schools: JavaScript Math Object
• w3schools: JavaScript Math Reference
• Mozilla Developer’s Network: Math

Math.pow

The pow method in Math raises a number to its exponent. It uses two numbers to do this – the base number and the power to raise it to (square, cube, etc.). It looks like this:

Math.pow(2,2) = 4;
Math.pow(3,2) = 9;
Math.pow(3,3) = 27;

Rounding decimals in JavaScript

The Math object has many methods in it. Some of these are used for rounding numbers. They are Math.round, Math.floor and Math.ceil and will round decimal numbers to the nearest whole number.

• Math.round works in the manner that most people are familiar with – if a decimal is .50 or higher, it rounds up to the next whole number. If its .49 or lower, it rounds down.
• Math.floor always rounds down to the nearest whole number, so 99.99 would round to 99, not 100.
• Math.ceil (or ceiling) does the opposite of .floor. It rounds up to the nearest whole number, regardless of the value of the decimal (as long as its not .00). So, 9.01 would round up to 10.

Math.round(6.5) = 7;
Math.round(6.45) = 6;
Math.floor(6.999) = 6;
Math.ceil(6.0001) = 7;

• Lambda School Full-Stack/Web Developer Pre-course Index