Ashish MehraAll 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.
