// 0 -> 10
const rand1 = Math.floor(Math.random() * 11);
// 1 -> 10
const rand2 = Math.floor(Math.random() * 10) + 1;
// 5 -> 20
const rand3 = Math.floor(Math.random() * 16) + 5;
// -10 -> (-2)
const rand4 = Math.floor(Math.random() * 9) - 10;
console.log(rand1);
console.log(rand2);
console.log(rand3);
console.log(rand4);

Math.random()

Returns an integer random number between min (included) and max (included):

function randomInteger(min, max) {
 return Math.floor(Math.random() * (max - min + 1)) + min;
}

Or any random number between min (included) and max (not included):

function randomNumber(min, max) {
 return Math.random() * (max - min) + min;
}

Useful examples (integers):

// 0 -> 10
Math.floor(Math.random() * 11);
// 1 -> 10
Math.floor(Math.random() * 10) + 1;
// 5 -> 20
Math.floor(Math.random() * 16) + 5;
// -10 -> (-2)
Math.floor(Math.random() * 9) - 10;

** And always nice to be reminded (Mozilla):

Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to security. Use the Web Crypto API instead, and more precisely the window.crypto.getRandomValues() method.

Math.random()

Returns an integer random number between min (included) and max (included):

function randomInteger(min, max) {
 return Math.floor(Math.random() * (max - min + 1)) + min;
}

Or any random number between min (included) and max (not included):

function randomNumber(min, max) {
 return Math.random() * (max - min) + min;
}

Useful examples (integers):

// 0 -> 10
const rand1 = Math.floor(Math.random() * 11);
// 1 -> 10
const rand2 = Math.floor(Math.random() * 10) + 1;
// 5 -> 20
const rand3 = Math.floor(Math.random() * 16) + 5;
// -10 -> (-2)
const rand4 = Math.floor(Math.random() * 9) - 10;
console.log(rand1);
console.log(rand2);
console.log(rand3);
console.log(rand4);

** And always nice to be reminded (Mozilla):

Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to security. Use the Web Crypto API instead, and more precisely the window.crypto.getRandomValues() method.

#Math.random()

Returns an integer random number between min (included) and max (included):

function randomInteger(min, max) {
 return Math.floor(Math.random() * (max - min + 1)) + min;
}

Or any random number between min (included) and max (not included):

function randomNumber(min, max) {
 return Math.random() * (max - min) + min;
}

Useful examples (integers):

// 0 -> 10
Math.floor(Math.random() * 11);
// 1 -> 10
Math.floor(Math.random() * 10) + 1;
// 5 -> 20
Math.floor(Math.random() * 16) + 5;
// -10 -> (-2)
Math.floor(Math.random() * 9) - 10;

** And always nice to be reminded (Mozilla):

Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to security. Use the Web Crypto API instead, and more precisely the window.crypto.getRandomValues() method.

Math.random()

Returns an integer random number between min (included) and max (included):

function randomInteger(min, max) {
 return Math.floor(Math.random() * (max - min + 1)) + min;
}

Or any random number between min (included) and max (not included):

function randomNumber(min, max) {
 return Math.random() * (max - min) + min;
}

Useful examples (integers):

// 0 -> 10
Math.floor(Math.random() * 11);
// 1 -> 10
Math.floor(Math.random() * 10) + 1;
// 5 -> 20
Math.floor(Math.random() * 16) + 5;
// -10 -> (-2)
Math.floor(Math.random() * 9) - 10;

** And always nice to be reminded (Mozilla):

Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to security. Use the Web Crypto API instead, and more precisely the window.crypto.getRandomValues() method.

#Math.random()

From the Mozilla Developer Network documentation:

// Returns a random integer between min (include) and max (include)
Math.floor(Math.random() * (max - min + 1)) + min;

Useful examples:

// 0 - 10
Math.floor(Math.random() * 11);
// 1 - 10
Math.floor(Math.random() * 10) + 1;
// 5 - 20
Math.floor(Math.random() * 16) + 5;
// -10 - (-2)
Math.floor(Math.random() * 9) - 10;

#Math.random()

Returns an integer random number between min (included) and max (included):

function randomInteger(min, max) {
 return Math.floor(Math.random() * (max - min + 1)) + min;
}

Or any random number between min (included) and max (not included):

function randomNumber(min, max) {
 return Math.random() * (max - min) + min;
}

Useful examples (integers):

// 0 -> 10
Math.floor(Math.random() * 11);
// 1 -> 10
Math.floor(Math.random() * 10) + 1;
// 5 -> 20
Math.floor(Math.random() * 16) + 5;
// -10 -> (-2)
Math.floor(Math.random() * 9) - 10;

** And always nice to be reminded (Mozilla):

Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to security. Use the Web Crypto API instead, and more precisely the window.crypto.getRandomValues() method.