Difference Between == and === in JavaScript

        var myNum = 5;
        var otherNum = 6;
        var notNum = "5";

        if(myNum == notNum){
            console.log("true");
        }
        else {
            console.log("false");
        }

myNum은 int이고

notNum은 string이지만

타입 변환(Type coercion)이 돼서 결국 myNum과 notNum이 같은 것으로 여겨짐

-> true값이 나옴

 

Type coercion is the automatic or implicit conversion of values from one data type to another (such as strings to numbers).

https://developer.mozilla.org/en-US/docs/Glossary/Type_coercion

Type coercion - MDN Web Docs Glossary: Definitions of Web-related terms | MDN

 

        if(myNum === notNum){
            console.log("true");
        }
        else {
            console.log("false");
        }

하지만 myNum과 notNum이 strictly equal은 아니기 때문에

=== Triple equals로 하면 false값이 나옴

Strict equality (===)

The strict equality operator (===) checks whether its two operands are equal, returning a Boolean result. Unlike the equality operator, the strict equality operator always considers operands of different types to be different.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Strict_equality

Strict equality (===) - JavaScript | MDN