In JavaScript, the qual value operator (==) is used to check whether a variable is equal to a value or not. Example
let p = "20";
if (p ==20){
alert("yes");
}
Looking at this code, p is actually qual to 20.
But if the if statement is like this
if (p === 20) it won't alert yes why?
Because, our strict equality or qual type and qual value operator also checks whether the values are of the same data types or not. Our "20" is a number string but what we passed in our logic is just a number.

Strict equality is really helpful, it helps you to avoid unnecessary bugs in your Codes. You can use lose quality but you have to be care on the data types.