Introduction to JavaScript Syntax (Part 2)

Introduction to JavaScript Syntax (Part 2)

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Hi there,

This is a second of our series on JavaScript syntax. If you haven't viewed the first part. Follow the link =>

For this tutorial, we will be going farther into the syntax. Here we will discuss Comparison operations, If and Switch Statements.

Let's go!

Comparison Operations

Comparison operations as the name implies involves the check done between two values for any of the following conditions.

  • == (equal to)
  • === (strictly equal to)
  • < (less than)
  • <= (less than or equal to)
  • > (greater than)
  • >= (greater than or equal to)

Comparison can be between any data type. For example.

console.log("meat" == "meat") //this will give True

The different between equal to and strictly equal to is this below.

console.log(2 === "2") //this will give False
console.log(2 == "2") //this will give True

In the example above, the first results in False because the triple equal sign is used to strictly compare two values. Which means it also checks the data type. If the data types are not the same, even if the numbers look the same. It will be false. In this case the first 2 is a number data type while the second "2" is a string data type.

However in the other example, 2 == "2" will give True because, the double equals does not check the data type, instead it does something called Type Coercion. This means that in the background, the == (double equals sign), forces both types to be the same and then compares their values. Hence, when "2" is 'coerced' is becomes 2 and become equal to the number 2.

Other comparison checks are pretty straightforward.

console.log(2 > 3) // false
console.log(2 >= 1) // true
console.log(2 < 5) // true

If Statements

Comparison checks and if statements work closely together. The if is a keyword in JavaScript used for checking whether a condition is true or not. if statements are used to execute code based on a particular condition or set of conditions.

The format for if statements is:

if (condition) {
// do this

For instance, if we want to give users information based on their age we can write a code like this:

let userAge = 18

if(userAge >= 18) {
   console.log("Welcome aboard!")

We can also do something else if the initial condition is not true using another keyword else. i.e

if(condition is true){
   // do something here
}else {
  // do something different

Using our previous example,

let userAge = 18

if(userAge >= 18){
   console.log("Welcome aboard!")
}else {
   console.log("You're not allowed  here!")

// welcome aboard

We could also check more conditions using the else if keyword.

if(condition is true){
   //do something
}else if (another condition is true){
   // do something else
} else {
   // do this if all fails

Continuing with the previous example,

let userAge = 18

if(userAge == 18){
   console.log("You are right on age!")
}else if(userAge > 18){
   console.log("You are above the age!")
}else {
   console.log("You are below the age!")

//you are right on age!

Switch Statements

Similar to if statements switch statements also help us take action based on 'truthi-ness' of a condition. switch statements are usually preferred when the number of conditions are long. They are used in the format:

    case value1:
          //do something
    case value2:
          //do something 
     case value3:
          //do something
          //do this if all fails


let today = new Date().getDay() // this gives the value of today between 0 - 6

switch (today) {
  case 0:
    day = "Sunday";
  case 1:
    day = "Monday";
  case 2:
     day = "Tuesday";
  case 3:
    day = "Wednesday";
  case 4:
    day = "Thursday";
  case 5:
    day = "Friday";
  case 6:
    day = "Saturday";

A Quick Recap

We looked at Comparison operators which are used to compare two values and returns true or false based on the comparison. These can also be used in if statements which allows you take action in your code based on a condition's truthiness. And then there are switch statements which can also function like if statements.