Search⌘ K
Home
Courses
Rediscovering JavaScript: ES6, ES7 & ES8

Use === Instead of ==

Understand the differences between == and === operators in JavaScript, and learn why === provides strict equality checks without type coercion. This lesson helps you avoid common pitfalls by using === for accurate comparisons, improving code reliability and preventing unexpected results.

We'll cover the following...

Many JavaScript programmers often repeat the mistake of comparing using ==, which is the type-coercion non-strict equality operator.

Example of == operator

Let’s look at an example that shows why using == may be a bad idea.

Javascript (babel-node)
const a = '1';
const b = 1;
const c = '1.0';
console.log(a == b);
console.log(b == c);
console.log(a == c);

Explanation

In the short piece of code given above, the constants a, b, and c have the values ‘1’, 1, and ‘1.0’, respectively. One value is of number type, and the other two are of string type. The last three lines of code compare each combination of constants.

Suppose a is equal to b and b is equal to ...