Different Cases of "===" and "=="

In JavaScript we have two type of equality comparison operators.

Non-strict and Strict

The difference between them is a very common question in
javascript interview. This blog will help you to review all the cases and understand the distinction.

• Non-strict (==) compare the values after converting the operands value to numbers

"1" == 1 // true

In the above example "1" on the left side will be converted to
number 1 .Hence, The Result will be true .

Different Cases :

1. " " == false // true
   In programming terms false is 0 and true is 1.
   " " and false will be converted to 0 which result into True.

2. 0 == false // true
   false will be converted to 0

3. 2 <= "4" // true

4. null == undefined // true
   This case is pretty different from other case . If we convert
   "undefined" to number the result will be NaN whereas in null
   case it will be converted to 0.

   So how this NaN == 0 can be result into true ?
   "Null" and "undefined" are empty values and its javascript
   core behaviour which result this into true.

5. NaN == NaN
   NaN is not equal to anything, including NaN

• Strict(===) compare the value without convertions, which is quite useful to overcome cases like 0 == false

" 1 " === 1 // false

In the Above example the strict operator (==) does not convert
the operand type to number. Thus , the output is false.

Different Cases :

1. Two strings are strictly equal when they have the same
   sequence of characters, same length, and same characters in
   corresponding positions.

   "abc" === "abc" // true
"abc" === "abcc" // false
"abc" === "acb" // false

2. Two Boolean operands are strictly equal if both are true or
   
   both are false.
   true === true //true
true === 1 //false

3. Two objects are strictly equal if they refer to the same
   Object.
   {} === {} //false

4. Null and Undefined types are not equal with ===, but equal
   with ==.
   null == undefined // true
null === undefined // false

Thanks for your read 🙌