Understanding Javascript equality == vs ===

Loose equality using ==

This operator compares two values for equality. (==) does not care about data types as it implicitly converts the value.

Example

'2' == 2 // true '' == 0 // false 0 == '' // true false == '0' // true false == 'false' // false ' \t\r\n ' == 0 // true 

Strict equality using ===

Is very strict and cares about the datatypes.

Value conversion does not happen in this instance. If the values have a different type they are evaluated as false

Example

'2' === 2 //false '' === 0 //false //Comparing operands of the same Type console.log("hello" === "hello"); // true console.log("hello" === "hola"); // false console.log(3 === 3); // true console.log(3 === 4); // false console.log(true === true); // true console.log(true === false); // false console.log(null === null); // true 

Strict equality makes your code more robust there are no underlying value changes that may after your conditions.

Rules

• If the operands are of different types, return false.
• If both operands are objects, return true only if they refer to the same object.
• If both operands are null or both operands are undefined, return true. -If either operand is NaN, return false. (Numbers must have the same numeric values. +0 and -0 are considered to be the same value.)
• Strings must have the same characters in the same order.
• Booleans must be both true or both false.

Reference [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Equality_comparisons_and_sameness]