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Equality Comparisons

Table of Content

Comparison Operators

Comparison operators are used in logical statements to determine equality or difference between variables or values.

Given that x = 10, the table below explains the comparison operators:

Name of Operator Operator Descriptions Usage Returns
Equality == equal to x == 15, x == 10, x == "10" false, true, true
Inequality != not equal to x != 15 true
Strict equality === equal value and equal type x === 10, x === "10" true, false
Strict inequality !== not equal value or not equal type x !== 10, x !== "10", x !== 15 false, true, true
Greater > greater than x > 5, x > 15 true, false
Less < less than x < 15, x < 5 true, false
Greater or equal >= greater than or equal to x >= 5, x >= 15 true, false
Less or equal <= less than or equal to x <= 15, x <= 5 true, false

Logical Operators

Logical operators are used to determine the logic between variables or values.

Given that x = 5 and y = 10, the table below explains the logical operators:

Name of Operator Operator Descriptions Usage Returns
AND && logical and (x<7 && y>9), (x<3 && y>9), (x==7 && y>15) true, false, false
OR || logical or (x==7 || y>9), (x<3 || y<9) true, false
NOT ! logical not !(x == y), x<y, x>y true, true, false

Conditional (Ternary) Operator

JavaScript also contains a conditional operator that assigns a value to a variable based on some condition.

let x = age < 18 ? "Young" : "Old";

If the variable age is a value below 18, the value of the variable x will be "Young", otherwise the value of x will be "Old".

The Nullish Coalescing Operator

The ?? operator returns the first argument if it is not nullish (null or undefined). Otherwise it returns the second argument.

let name1 = null;
let name2 = "Emre";
let name = name1 ?? name2; // It returns "Emre"

--------------------------------------------------

let name1 = "Mahmut";
let name2 = "Emre";
let name = name1 ?? name2; // It returns "Mahmut"

The Optional Chaining Operator

The ?. operator returns undefined if an object is undefined or null instead of throwing an error.

const person = {
  name: "Mahmut",
  dog: {
    name: "Chucky",
    color: "Black",
  },
  cat: {
    name: "Cindy",
  },
};

console.log(person.dog?.color); // It returns "Black"
console.log(person.cat?.color); // Undefined

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