The general syntax for this method is:
This method returns a random decimal value between 0 and 1, which can be stored in a variable or used in a calculation.
Note that 0 is a possible selection, but 1 is NOT.
0.34992592600591066 0.11861535165960668 0.019710093901842862 0.7751799992655235 0.46782849511194136
Generate a Random Integer
If a random integer must be generated, the result of
Math.random() can be
manipulated with operators (
+, -, *, /) and other
The trick to creating a random integer is to multiply
Math.random() by a
whole number and then round the result to remove the decimal portion. The
choice of using the
round method affects the
Explore the example below:
floor = 0, ceil = 1, round = 0 floor = 6, ceil = 7, round = 7 floor = 2, ceil = 3, round = 3 floor = 8, ceil = 9, round = 8 floor = 9, ceil = 10, round = 10
Math.random() by 10, applying the
floor method gives
numbers between 0 and 9. Using the
ceil method shifts the range up one
digit, generating values between 1 and 10. Using the
round method gives the
widest range, generating numbers between 0 and 10.
Rather than trying to remember which method to use, one choice is to ALWAYS
floor to round to an integer:
Math.floor(Math.random()*10)generates a number from 0 - 9.
Math.floor(Math.random()*120)generates a number from 0 - 119.
To start our range at 1, just add 1 to the rounded value:
Math.floor(Math.random()*10) + 1generates a number from 1 - 10.
Math.floor(Math.random()*120) + 1generates a number from 1 - 120.
By changing the value that multiplies
Math.random() we specify the range
for the numbers we want to generate.
Math.floor(Math.random()*maxValue)generates a number from 0 to (
Math.floor(Math.random()*maxValue) + 1generates a number from 1 to