Avoid boolean values comparison with "==" in JavaScript

All of us use "==" daily for performing the comparison in JavaScript to execute particular code block only when certain condition meets.

But do you know how "==" actually works in JavaScript?

In JavaScript "==" compare number values instead of boolean values by performing implicit coercion.

Here is a simple example :

 const a = 10;

 if(a == "10"){
     console.log("Woo! Condition is true.");
 }

In above block of code we're comparing string value of "10" with a integer value of const variable a which is 10.
So here, JavaScript will first perform implicit coercion on non-number type value i.e. "10" and will convert it into a number and then perform comparsion.

Why you should avoid comparison of boolean values with "=="?

We are now aware of the fact that "==" compare integer value type not boolean type.So comparing boolean values with "==" will not give desired result to you every time.

Examples of Wrong Implementation for value check :

Example 1

const a = 10;

if(a == true){
    console.log("Condition is true.");
}else{
    console.log("Condition is false.");
}

Number equivalent of true is 1.
False : 10 is not equal to 1.

Example 2

const a = "1";

if(a == true){
    console.log("Condition is true.");
}else{
    console.log("Condition is false.");
}

Number equivalent of true is 1 and a is 1.
True : 1 is equal to 1.

Examples of Correct Implementation for value check :

Example 1

const a = 10;

if(a){
    console.log("Condition is true.");
}else{
    console.log("Condition is false.");
}

True : Because the boolean equivalent of a is true.

Example 2

const a = "1";

if(a){
    console.log("Condition is true.");
}else{
    console.log("Condition is false.");
}

True : Because the boolean equivalent of a is true.

Example 3

const a = "";

if(a){
    console.log("Condition is true.");
}else{
    console.log("Condition is false.");
}

False : Because the boolean equivalent of a is false.

Conclusion

Try to avoid using boolean values comparison with "==". It will work for you in many cases but it is not a right way to perform a condition check.

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Avoid boolean values comparison with "==" in JavaScript

Ashish Mehra

Why you should avoid comparison of boolean values with "=="?

Examples of Wrong Implementation for value check :

Examples of Correct Implementation for value check :

Conclusion

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