JavaScript Random
Posted: Fri Oct 27, 2023 9:07 am
JavaScript Random
Math.random()
Math.random() returns a random number between 0 (inclusive), and 1
(exclusive):
Example
// Returns a random number:
Math.random();
Try it Yourself »
Math.random() always returns a number lower than 1.
JavaScript Random Integers
Math.random() used with Math.floor() can be used to return random integers.
There is no such thing as JavaScript integers.
We are talking about numbers with no decimals here.
Example
// Returns a random integer from 0 to 9:
Math.floor(Math.random() * 10);
Try it Yourself »
Example
// Returns a random integer from 0 to 10:
Math.floor(Math.random() * 11);
Try it Yourself »
Example
// Returns a random integer from 0 to 99:
Math.floor(Math.random() * 100);
Try it Yourself »
Example
// Returns a random integer from 0 to 100:
Math.floor(Math.random() * 101);
Try it Yourself »
Example
// Returns a random integer from 1 to 10:
Math.floor(Math.random() * 10) + 1;
Try it Yourself »
Example
// Returns a random integer from 1 to 100:
Math.floor(Math.random() * 100) + 1;
Try it Yourself »
A Proper Random Function
As you can see from the examples above, it might be a good idea to create a proper random function
to use for all random integer purposes.
This JavaScript function always returns a random number between min (included) and
max (excluded):
Example
function getRndInteger(min, max) {
return Math.floor(Math.random() * (max - min) ) + min;
}
Try it Yourself »
This JavaScript function always returns a random number between min and max (both included):
Example
function getRndInteger(min, max) {
return Math.floor(Math.random() * (max - min + 1) ) + min;
}
Try it Yourself »
★
+1
Reference: https://www.w3schools.com/js/js_random.asp
Math.random()
Math.random() returns a random number between 0 (inclusive), and 1
(exclusive):
Example
// Returns a random number:
Math.random();
Try it Yourself »
Math.random() always returns a number lower than 1.
JavaScript Random Integers
Math.random() used with Math.floor() can be used to return random integers.
There is no such thing as JavaScript integers.
We are talking about numbers with no decimals here.
Example
// Returns a random integer from 0 to 9:
Math.floor(Math.random() * 10);
Try it Yourself »
Example
// Returns a random integer from 0 to 10:
Math.floor(Math.random() * 11);
Try it Yourself »
Example
// Returns a random integer from 0 to 99:
Math.floor(Math.random() * 100);
Try it Yourself »
Example
// Returns a random integer from 0 to 100:
Math.floor(Math.random() * 101);
Try it Yourself »
Example
// Returns a random integer from 1 to 10:
Math.floor(Math.random() * 10) + 1;
Try it Yourself »
Example
// Returns a random integer from 1 to 100:
Math.floor(Math.random() * 100) + 1;
Try it Yourself »
A Proper Random Function
As you can see from the examples above, it might be a good idea to create a proper random function
to use for all random integer purposes.
This JavaScript function always returns a random number between min (included) and
max (excluded):
Example
function getRndInteger(min, max) {
return Math.floor(Math.random() * (max - min) ) + min;
}
Try it Yourself »
This JavaScript function always returns a random number between min and max (both included):
Example
function getRndInteger(min, max) {
return Math.floor(Math.random() * (max - min + 1) ) + min;
}
Try it Yourself »
★
+1
Reference: https://www.w3schools.com/js/js_random.asp