Comparison Operators

JavaScript is what's considered to be a loosely-typed language. In other words, the programmer does not need to specify the type (integer, string, etc.) of a variable or object, or the return type of a function for that matter. With that said, there are two types of comparison operators in JavaScript - strict and type-converting.

Equality Operators

With a type-converting comparison, we use ==, or the "double-equals" to compare two items. The interpreter will convert both operands in question into the same type. From there it will then perform a strict comparison. As we can see below, number has a value of 5, and numberAsAString has a value of "5". Once the interpreter converts them to the same type, either string or integer, it returns true, as both values are equal.

// type-converting comparison

const number = 5;

const numberAsAString = "5";

number == numberAsAString // returns true

With a strict comparison, we use ===, or the "triple-equals" to compare two items. The interpreter does not give you the luxury of converting both operands to the same type. It strictly checks if they're the same type - and if so, it will then check if their values are equal. Otherwise, it returns false. Here's an example:

// strict comparison

const number = 5;

const numberAsAString = "5";

number == numberAsAString // returns false;

Comparing Objects

It's important to note that when comparing objects, the interpreter does not just compare the values - it compares the objects reference in memory.

let thisObj = { id: 5 };

let thatObj = { id: 5 };

thisObj == thatObj // returns false

thisObj === thatObj // returns false

let theOtherObj = thisObj;

thisObj == theOtherObj; // returns true

thisObj === theOtherObj; // returns true

Inequality Operators

On the other hand, we have inequality (!=) and strict inequality (!==) operators.

In a similar fashion, the inequality operator will check if two items are not equal, whilst ignoring type.

let myNumber = 100;

let myString = "50";

myNumber != myString // returns true

The strict inequality operator will check the types of both operands. If they're different types, then it will return true as they're not equal. If they are of the same type, but their respective values are different, it will return true.

let itemA = 3;

let itemB = "3";

itemA !== itemB // returns true

Relational Operators

Lastly, we have the relational operators which may look familiar:

• < is the 'less than' operator
• > is the 'greater than' operator
• <= is the 'less than or equal to' operator
• >= is the 'greater than or equal to' operator

let foo = 5;

let bar = 10;

let baz = 10;

foo < bar // returns true

foo > bar // returns false

bar >= baz // returns true

bar <= baz // returns true

Wrapping Up ✅

Comparison operators are certainly one of the fundamentals of programming as they allow us to compare values in our logic to one another and execute code based off of the result that's the returned.

Stay Tuned 📺

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