Course Prerequisites

This course assumes familiarity with the following JavaScript concepts:

• Variables
• Functions
• Function invocation
• Loops and data structure
• Basic HTML and CSS

A low-level approach is taken to explain concepts and code with a lot of hands-on practice to help developers master the concepts taught. Here’s a quick refresher on some JavaScript concepts and knowledge necessary to understand the course.

Variable declaration

A variable is used to store data in a program. It’s declared using the const or the let keyword followed by the variable’s name.

const name = "Brandon Rodgers";
let age = 23;
//variable declared with const can not be reassigned while those with let can.

Function declaration

A function is a set of statements or blocks of code that perform a particular task. A function should only perform one task. To declare a function, use the function keyword followed by the function’s name with parenthesis for the arguments. The set of instructions or statements in a function is written inside curly brackets ({})

function showName() {
   return "Mikel Arteta";
}
//a function can return a value or not

Function expression

A function expression assigns a function to a variable. A function assigned to a variable doesn’t need a name. We reference it using the variable name.

const showName = function() {
   return "Mikel Arteta";
}

Function invocation

We must use a function after defining it. This is done by invoking the function. A function is invoked by adding parentheses after the function name. Any arguments the function needs are added inside the parentheses.

const showName = function() {
   return "Mikel Arteta";
}
let name = showName() //returns Mikel Arteta

Arrow function

An arrow function is another way to declare a function in JavaScript. Arrow functions allow for the writing of shorter syntax.

 const showName = () => {
    return "Mikel Arteta";
 }

Loops

A loop is a repetition. Loops are used to perform a repeated task based on conditions.

For loops

A for loop is very common in JavaScript. It takes a starting index that’s usually denoted as i followed by the condition. The example below states that because i < 10, we should run the code inside the curly brackets. The third part of the loop is how we increment or decrement the loop. This is denoted as i++.

for (let i = 0; i < 10; i++) {
 //do something with each value of i
}

While loop

A while loop performs a task as long as the condition contained in the parenthesis remains true. A while loop is usually preferred when we aren’t sure about the number of times we have to perform a loop. We have to be careful when using a while loop to avoid running into an infinite loop.

let number = 10;
while ( number < 10 ) {
 //do something here
 //decrement number here to prevent an infinite loop
 number--;
}

Arrays and objects

An array is like a bucket list that can hold more than one item. Arrays normally start with the 0 index. This means that the first item in the array is at position 0.

Objects represent key-value pair data stored in a curly bracket.

let names = ["Happy", "Etse", "Savior"]
//array of names

let person = {
  name: "Cynthia Bernard",
  age: 19,
  sex: "female",
  occupation: "Nurse",
  address: "West Minister Point, London"
}
//person object

A module is dedicated to a quick JavaScript refresher that will keep us informed of what we need to be familiar with when coding ReactJS components for the front-end of our MeteorJS web application. (ReactJS is an open-source JavaScript library used to build user interfaces in a declarative way. )